Functional Textiles and Clothing 2023: Proceedings of 3rd International Conference on Functional Textiles & Clothing 2023 (Springer Proceedings in Materials, 42) 9819999820, 9789819999828

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Springer Proceedings in Materials

Deepti Gupta Abhijit Majumdar Sanjay Gupta   Editors

Functional Textiles and Clothing 2023 Proceedings of 3rd International Conference on Functional Textiles & Clothing 2023

Springer Proceedings in Materials Volume 42

Series Editors Arindam Ghosh, Department of Physics, Indian Institute of Science, Bengaluru, India Daniel Chua, Department of Materials Science and Engineering, National University of Singapore, Singapore, Singapore Flavio Leandro de Souza, Universidade Federal do ABC, Sao Paulo, São Paulo, Brazil Oral Cenk Aktas, Institute of Material Science, Christian-Albrechts-Universität zu Kiel, Kiel, Schleswig-Holstein, Germany Yafang Han, Beijing Institute of Aeronautical Materials, Beijing, Beijing, China Jianghong Gong, School of Materials Science and Engineering, Tsinghua University, Beijing, Beijing, China Mohammad Jawaid , Laboratory of Biocomposite Technology, INTROP, Universiti Putra Malaysia, Serdang, Selangor, Malaysia

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Deepti Gupta · Abhijit Majumdar · Sanjay Gupta Editors

Functional Textiles and Clothing 2023 Proceedings of 3rd International Conference on Functional Textiles & Clothing 2023

Editors Deepti Gupta Department of Textile Technology Indian Institute of Technology Delhi New Delhi, Delhi, India

Abhijit Majumdar Department of Textile and Fibre Engineering Indian Institute of Technology Delhi New Delhi, Delhi, India

Sanjay Gupta World University of Design Sonipat, India

ISSN 2662-3161 ISSN 2662-317X (electronic) Springer Proceedings in Materials ISBN 978-981-99-9982-8 ISBN 978-981-99-9983-5 (eBook) https://doi.org/10.1007/978-981-99-9983-5 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Singapore Pte Ltd. The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore Paper in this product is recyclable.

Contents

Protective and Adaptive Clothing Light-Weight Indigenously Developed Firefighter Suit . . . . . . . . . . . . . . . . M. S. Parmar and Nidhi Sisodia

3

Developing Functionality in Geriatric Wear Through Designing . . . . . . . Monisha Singh and Sangita Srivastava

13

Advanced Activated Carbon Adsorbent Filter Material for Chemical Protective Clothing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Himanshi Dhyani, Ravindra V. Adivarekar, Vikas B. Thakare, Suraj Bharati, Pushpendra K. Sharma, Kaveri Agrawal, Atul K. Sonkar, and Prabhat Garg

25

Clothing for the Visually Impaired . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Udita Shree and Ankita S. Pandey

41

Designing Adaptive Sportswear Based on Biomechanical Needs . . . . . . . . Subhalakshmi Kropi Bhuyan and Nilanjana Bairagi

51

Design and Development of Functional Clothing for the Visually Challenged . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ameesha Goel, Pranati Aggarwal, and Srivani Thadepalli

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Plus Size Women Body Shape Analysis: An Implication for Developing a Sizing System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Annu Kumari and Noopur Anand

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Investigation of the Pressure Transmission Characteristics of Miniaturised Air Bladders for Medical Compression Textiles . . . . . . . . D. P. Hedigalla, M. Ehelagasthenna, G. K. Nandasiri, I. D. Nissanka, and Y. W. R. Amarasinghe

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Contents

Eco-Friendly Dyeing and Finishing Eco-Friendly Dyeing and Finishing for Improving Colour Fastness and Wellness Properties of Cotton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 Pubalina Samanta, Asis Mukhopadhyay, and Adwaita Konar Optimisation of Fire-Retardant Finishing of Cotton with Ammonium Sulfamate and Sodium Stannate by User-Defined Quadratic Empirical Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 Ashis Kumar Samanta, Ayan Pal, and Tapas Ranjan Kar Simultaneous Dyeing and Finishing of Bio-mordanted Cotton . . . . . . . . . 171 Yamini Dhanania, Deepali Singhee, and Ashis Kumar Samanta Functionalization of Jute to Improve Colour Yield and Fastness of Annatto Dye . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 Ritwik Chakraborty, Ashis Kumar Samanta, and Padma Shree Vankar Development of Woven PPE with Regenerated Fibers to Enhance the Comfort Properties of the Wearer with Antimicrobial and Liquid Barrier Nano Particle Finish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 J. M. Subashini and G. Ramakrishnan Surface Modification Techniques in Textiles: A Review . . . . . . . . . . . . . . . . 225 S. Periyasamy, Deepti Gupta, M. Parvathi, and Satyajeet B. Chaudhari Sustainable Fibres and Products Development of Nettle Fibre Blended Apparel Textiles . . . . . . . . . . . . . . . . 235 Kartick K. Samanta, A. N. Roy, H. Baite, S. Debnath, L. Ammayappan, L. K. Nayak, A. Singha, and T. Kundu A Study on the Application of Weaver Ant Silk in Wound Healing . . . . . . 249 P. Kandhavadivu, S. Sudha, and B. Charmini Study on the Rustling Sound of Various Fabrics and Their Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261 V. Prithvi, R. Priyanka, N. Sadvika, and S. Sundaresan Development of Flax and Silk Blended Yarn in the Wet Spinning System and Comfort Characterization of Blended Fabrics . . . . . . . . . . . . . 265 Brojeswari Das, Sreenivasa, Y. C. Radhalakshmi, S. K. Som, and A. T. Bindu Study of Sisal Nonwoven Mulching for Watermelon Cultivation and Its Effect on Soil Nutrition Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277 Janki R. Patel, Tasnim N. Shaikh, and Bharat H. Patel

Contents

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Development of Cost-Effective, Eco-Friendly Sanitary Pads for Better Health and Sanitation of Rural Women . . . . . . . . . . . . . . . . . . . . 289 R. Niveda and G. Ramakrishnan Decoding the Science Behind the Chemical Recycling of Textiles . . . . . . . 295 Sweta Singh and Prabir Jana

About the Editors

Deepti Gupta is Professor in the Department of Textile and Fibre Engineering at the Indian Institute of Technology Delhi, India. She has more than 35 years of teaching and research experience. Dr. Gupta works in the area of surface functionalization and eco-friendly finishing of textiles, microbe-resistant textiles, functional clothing, and garment sizing. She has published more than 100 papers in national and international journals of repute, edited six books, and contributed several chapters to books. She has been featured on the Stanford University list of 2% of most cited material scientists for the years 2020–2023. She has guided 12 Ph.D. students. She along with her team was awarded the “Biotech Product and Process Development and Commercialisation Award 2020” by the Department of Biotechnology, Government of India, and was awarded the “Outstanding Alumna Award” in 2018. Dr. Gupta is Founder Mentor of a wearable health-tech start-up company and Chair of the Organising Committee of the Biannual Conference on Functional Textiles and Clothing (FTC). Abhijit Majumdar holds the position of Chair Professor for Decision Sciences in the Textile and Fibre Engineering Department at the Indian Institute of Technology, Delhi, India (IIT Delhi). He graduated from Calcutta University in 1995 with a gold medal in Textile Technology. He also holds M.Tech. and MBA degrees from IIT Delhi. He acquired a Ph.D. in production engineering from Jadavpur University, Kolkata. He has 25 years of experience in academia and two years of experience in industry. He has authored two textbooks and edited five books. He has published 160 research papers in refereed journals which have received more than 6000 citations. He has also guided 15 Ph.D. scholars. He is one of the Editors of the Journal of the Textile Institute and an Area Editor of the Operations Management Research journal. He is the recipient of Eminent Engineer Award from the Institution of Engineers (India), Best Industry Relevant Masters Project Supervision Award, IIT Delhi (2019); Gandhian Young Technology Innovation (GYTI) Award (2016 and 2021); Teaching Excellence Award of IIT Delhi (2015) and Outstanding Young Faculty Fellowship, IIT Delhi (2009–2014).

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About the Editors

Sanjay Gupta is currently Professor and Vice-Chancellor at the World University of Design, Sonepat, India. Prior to this, he was Dean at the National Institute of Fashion Technology, India. He obtained his B.Tech. and Ph.D. in Textile Technology from the Indian Institute of Technology Delhi. He was a UNDP fellow at the Fashion Institute of Technology (FIT), New York, and a Visiting Professor at École Nationale Supérieure des Arts et Industries Textiles (ENSAIT), France. His research interests include functional clothing design and development of textile products. He has over 100 publications and over 30 presentations at national/international conferences and seminars.

Protective and Adaptive Clothing

Light-Weight Indigenously Developed Firefighter Suit M. S. Parmar and Nidhi Sisodia

Abstract The role of firefighters is very extensive in our society. Firefighters not only play a pivotal role in rescuing human lives during fire accidents but also save properties from extensive damage by extinguishing hazardous fires. It is one of the life-threatening occupations that require intensive physical work in a hazardous environment. No significant work is done to develop firefighter suits for firefighters indigenously. Under this study, an indigenous lightweight firefighter suit is developed as per the standard IS 16890 and EN 469. The developed suit has been made using four layers (outer, moisture barrier, thermal barrier, and lining). The flame spread index of the component assembly was found to be 3 when tested as per ISO 15025 and the heat transfer Index (HTI24 ) at 80 Kw/m2 heat flux of the component assembly was found to be 13.7 s. The Radiant Heat Index (RHTI24 ) at 40 kW/m2 of the component assembly was 27.3 s. There was no water or chemical penetration observed through the suit when tested as per EN 20,811 and ISO 6530, respectively. The water vapor resistance (Ret) was found to be 27.6 m2 Pa/W. The total weight of the large-size suit was found to be 3 kg only. Keywords Convective heat · Fire hazard · Radiant heat

1 Introduction The role of firefighters is to take quick action to extinguish an uncontrolled fire during a fire accident so precious human lives and property can be saved. To fulfill these tasks, firefighters have to work in extremely hazardous thermal environments [1]. For getting suitable firefighter clothing, it is required to balance two opposite properties—thermal protection and metabolic heat stress. For firefighter suits, higher thermal protection property is required with lower metabolic heat stress properties. Although thermal protection is one of the prime requirements, heat stress during M. S. Parmar (B) · N. Sisodia Northern India Textile Research Association, Sector-23, Rajnagar, Ghaziabad, Uttar Pradesh, India e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024 D. Gupta et al. (eds.), Functional Textiles and Clothing 2023, Springer Proceedings in Materials 42, https://doi.org/10.1007/978-981-99-9983-5_1

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M. S. Parmar and N. Sisodia

work affects the comfort properties of firefighter suits. As both these properties are opposite to each other, the selection of suitable fabrics for making firefighter suits is very challenging. In firefighting operations, there is always the possibility of protective work wear becoming wet as water is primarily used for fire extinguishing purposes. As the ambient temperature during firefighting operation remains very high with very high physical activities of firefighters, the firefighter perspires profusely. This makes clothing next to the skin saturated with perspiration. Some of the studies [2, 3] indicate that the absorption of moisture by the thermal layer and its dispersion in the thermal layer results in multiple effects on the transmission of heat through material used for thermal insulation. It was seen that during firefighting operations, in some instances, the steam is passed through the work wear and condenses on the skin thus causing burning injury. In another study [4], the effect of fabric weight and thickness on moisture vapor resistance value (Ret) is studied. Therefore, a balance should be made between heat and vapor transfer as higher weight and thickness help in reducing heat impact but reduce vapor transfer. Presently most firefighter suits are bulky, heavy, and less pliable thus reducing vapor permeability. Ultimately such suits increase physiological strain. Studies have also reported statistically that about 42% die due to too much workload, stresses due to excessive heat, and health-related issues. It is a well-known fact that the main aim of firefighter PPEs is to protect the wearer from thermal heat impact. To get this aim fulfilled there is a need to increase the weight and bulkiness of the PPE. The increase in weight and bulkiness, hinder the mobility of the wearer and ultimately affects the efficiency of the wearer with an increase in metabolic cost of work by up to 50% [5]. A firefighter suit is generally made out of three layers-outer, a moisture barrier, and a thermal barrier [6]. Sometimes liner fabric is also used to give a comfortable feel to the wearer. In the case of the outermost layer, it is made out of flameretardant materials, mostly using inherently flame-retardant fibers [7–9]. To reduce the cost of these inherently flame-retardant fibers (IFR) and improve comfort properties, other types of fibers are also blended with these. Some well know IFR fibers are aramids p-aramid and m-aramid, polybenzimidazole (PBI), polyethylene-2,6naphthalate (PEN), and p-phenylene-2,6-benzobisoxazole (PBO) [10]. Some earlier studies have shown that with the increase in para-aramid percentage in the blend, flame retardant property decreases. The value of p-aramid between 5 and 23% gives the optimum value of flame retardancy [11]. The moisture barrier present in the ensemble is to protect the firefighter from high-temperature steam, various chemicals, and selected pathogens. The mostly woven or nonwoven backing substrate with a permeable film or membrane layer is generally used as a moisture barrier. The third layer of the clothing is a thermal barrier to give protection from radiant heat and is mostly made out of a nonwoven or porous padding structure. Mostly EN 469 and NFPA 1971 standards are used to test firefighter suits. Out of these two, NFPA 1971 provides more specific requirements for the design of suits including trim configuration. The literature revealed that most of the studies on the development of firefighter suits revolved around providing thermal protection to decrease burn injuries and these efforts inevitably increased the weight and bulkiness of the firefighters’ protective

Light-Weight Indigenously Developed Firefighter Suit

5

system and ultimately compromised the mobility and comfort of the firefighter [12, 13]. In this present study, an indigenous lightweight and less bulky firefighter suit was developed.

2 Material and Methods The outer shell, moisture barrier, thermal barrier, and liner were used to develop the firefighter suit. Three rip stop weave fabrics of different areal densities were developed using NOMEX 3a fiber and coded as L1, L2, and L3. The yarn and fabric samples were manufactured at the NITRA pilot plant for preliminary study and bulk trials were taken at M/s Arvind Ltd. These fabric samples were laminated with ePTFE membrane at M/s Arvind Ltd so the outer layer also acts as a moisture barrier. Twelve samples (coded as T1 to T2) of woven and nonwoven thermal layers were developed using m-aramid fibers. Woven thermal layers were developed at the NITRA pilot plant. The weaving was done on a CCI sample loom (model no SL 8900 EG). Nonwoven samples were sourced from M/s Arvind Ltd. The flame-retardant lightweight lining fabric was manufactured at M/s Arvind Ltd using FR viscose and modacrylic blended yarn. The developed layers were combined to make one ensemble and tested for various properties like limited flame spread, contact heat, convective heat, radiant heat, tensile and tear strength, chemical penetration, and water resistance as per IS 16890/EN 469.

3 Results and Discussion All the layers developed are discussed below.

3.1 Outer Layer with Moisture Barrier Three types of outer layer fabrics coded as L1, L2, and L3 with moisture barrier were developed as given in Table 1. Nomex 3A fabric was used for developing these fabric samples. These fabric samples were laminated with PTFE PTFE-based membrane to have a moisture barrier effect. These fabric samples were tested for mass and thickness properties. From the table, it is clear that L1 has the lowest mass and thickness compared to L2 and L3. All the outer layer samples (L1, L2, and L3) were analyzed for flame retardance, water repellence, and chemical resistance properties. Following are the results of the flame spread test as per ISO 15025 Procedure A: – not a single specimen has given flaming to the top or either side edge;

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M. S. Parmar and N. Sisodia

Table 1 Physical properties of outer layers

– – – –

Outer layers

Areal density, g/m2

Thickness (1 kPa)

L1

166

0.33 mm

L2

265

0.42 mm

L3

187

0.34 mm

not a single specimen has shown hole formation; not a single specimen has shown flaming or molten debris; the mean value of after flame time: Nil; the mean value of the afterglow time: Nil.

From the above results, it is clear that all the outer layer samples meet the requirement of limited flame spread as per IS 16890/EN 469. All the samples were tested for water repellency test as per EN 24,920. All the samples meet the requirement of IS 16890/EN 469. The rating of all samples was found to be >4. Outer layer samples were tested for liquid chemical penetration test as per ISO 6530. Under this, chemicals are applied for 10 s using 30% H2 SO4, and 100% Xylene. As per the requirement mentioned in EN 469, there shall be no penetration of any of these chemicals to the innermost surface and the repellency rate shall be more than 80%. All the samples meet the requirement of chemical penetration as per EN 469. As a lightweight firefighter suit is always preferred, sample L1 is selected for further study as it has the lowest mass compared to others.

3.2 Thermal Barrier Twelve thermal barrier layers T1 to T12 were developed. These were tested for areal density (mass) and thickness. Results are given in Table 2. Analysis of Radiant Heat Transfer Index of the Thermal Layer. The radiant heat transfer index at 24 °C (RHTI24 ) is the most important parameter for the thermal layer. The radiant heat index is tested as per ISO 6942. The results of all 12 thermal layers are given in Table 3. From Table 3, it is clear that the radiant heat transfer index (RHTI24 ) of T8 (15.6), T9 (18.0), T10 (13.9), and T11 (15.9) are found to the higher than other thermal layers. Out of these four, T8 (432 g/m2 ), T9 (537 g/m2 ), and T11 (347 g/m2 ) are having high mass compared to T10 (225 g/m2 ). Therefore, this thermal layer (T10) was taken for further study.

Light-Weight Indigenously Developed Firefighter Suit

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Table 2 Physical properties of thermal layers Thermal layers

Fabric type

Fiber

Areal density, g/m2

Thickness, mm

T1

Woven

M-Aramid

217

1.34 mm

T2

Woven

M-Aramid

206

1.42 mm

T3

Woven

M-Aramid

254

1.45 mm

T4

Woven

M-Aramid

267

1.40 mm

T5

Woven

M-Aramid

305

1.49 mm

T6

Woven

M-Aramid

227

1.40 mm

T7

Woven

M-Aramid

234

1.70 mm

T8

Woven

M-Aramid (double layers)

432

2.03 mm

T9

Woven

M-Aramid (double layers)

537

2.52 mm

T10

Woven

M-Aramid

225

1.50 mm

T11

Non-woven

M-Aramid

347

2.22 mm

T12

Non-woven

M-Aramid

180

0.79 mm

Table 3 Radiant heat transfer index of different thermal layers Thermal layers

Incident heat flu x density, Qo

Radiant heat transfer index at 12° C (RHTI 12)

Radiant heat Transmitted transfer index heat flux at 24° C (RHTI density (Qc) 24)

T1

39.172

4.4

8.5

16.22

0.414

T2

39.172

5.0

9.3

15.47

0.395

T3

39.172

4.9

9.2

15.47

0.395

T4

39.172

5.0

9.3

15.47

0.395

T5

40.874

5.8

10.6

13.86

0.339

T6

38.642

5.6

10.2

14.46

0.374

T7

38.642

4.7

8.7

16.63

0.430

T8

38.139

9.1

15.6

10.23

0.265

T9

39.710

11

18.0

T10

40.874

8.0

13.9

11.28

0.275

T11

39.710

9.6

15.9

10.56

0.278

T12

41.976

4.5

8.2

17.98

0.428

9.642

Heat transfer factor (TF)

0.243

3.3 Liner Fabric FR viscose fabric was selected for liner fabric as it is more comfortable than others. It is coded as ‘Lf’. The liner fabric was after 5 washes for FR property as per ISO 15025 procedure A. In both cases, the sample meets the requirement of EN 469. The

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M. S. Parmar and N. Sisodia

thickness of the fabric was found to be 0.45 mm and tensile strength warps wise 638 N and weft wise 593 N. The tear strength of the fabric was found to be 29 N in both directions.

3.4 Combining All Layers All the layers (L1, T10, and Lf) were combined and tested for all the properties as per IS 16890/EN 469. The test report is given in Table 4. From the table, it is clear that combined layers meet the requirements of IS 16890/EN 469.

3.5 Development of Firefighter Clothing/Suit A two-piece garment (coat and trousers) easy to put on and easy to remove was developed at M/s Aeronav Industrial Safety Appliances, NOIDA. While fabricating this suit, it was considered that it should be comfortable for the wearer, well-fitted, and should cover most of the body. It should fit tightly at all openings, i.e., hand and leg. The detail of ergonomic considerations while designing a firefighter suit is given below as per IS 16890: – There shall not be any sharp or hard edges, rough surfaces, or other items on the inner or outer surface of the clothing that are likely to cause harm to the user. – The put-on and takes off of the firefighter suit should be without difficulty. – The firefighter suit should not be too tight for comfort and deep breathing should not be restricted and there should be nowhere any blood flow restriction. – The designing of the firefighter suit shall be done with the consideration of armholes and crotch being appropriately proportioned and positioned. – There shall be ease and security of closures and adjusters and this system shall remain intact during the movement of the wearer. – There shall be no difficulty while walking, kneeling, crawling, bending over, picking up the small objective, raising both hands above the head, and stair climbing. – The firefighter suit shall cover the body area to be protected during movements. – The firefighter suit shall be compatible with other items of PPE for example, gloves; boots should be possible without difficulty. The complete picture of the suit is shown in Fig. 1. The total weight of a large-size firefighter is 3 kg.

Light-Weight Indigenously Developed Firefighter Suit

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Table 4 Test results of combined layers as per IS 16890/ EN 469 Properties

Requirement

Test Results

Flame spread resistance as per No Specimen shall give Nil EN ISO 15025: 2002 flaming to the top or either side Procedure A edge

Heat Transfer (Convective heat) Heat Transfer (Radiation) as per EN ISO 6942

No specimen shall give hole formation in any layer

Nil

No specimen shall give flaming or molten debris

Nil

The mean value of after flame time shall be ≤2 s

Nil

The mean value of afterglow time shall be ≤2 s

Nil

Heat transmission index HTI24 HTI24 = 13.7 ≥ 13 HTI24 - HTI12 ≥ 4

HTI24 -HTI12 = 5.5

(RHTI24 ) t2 ≥ 18 s

HTI24 = 24.3 s HTI12 = 15.3 s

HTI24 -HTI12 ≥ 4 s

HTI24 -HTI12 = 9 s

Residual Strength of material Breaking load ≥ 450 N (In as per EN ISO 13934–1 or EN both directions) ISO 1421: 1998 method 1 after exposing radiant heat to 10 kW/m2 as per EN ISO 6942:2002 Method-A

Warp wise: 589 N Weft wise: 593 N

Heat Resistance (as per ISO 17493 at temperature 180 ± 5 °C using hot air circulating oven for 5 min)

Weft-wise: 0.8%, Warp wise: 0% No melting, dripping, ignition

Shall not melt, drip, separate, or ignite, and shall not shrink more than 5% in both directions

Tensile strength as per EN ISO Breaking load ≥ 450 N (In 13934–1 or EN ISO both directions) 1421:1998 Method-1

Warp wise:1056 N Weft wise: 987 N

Tear strength as per EN ISO 4674–1:2003

Tear strength ≥ 25 N (in both directions)

Warp wise:38.6 Weft wise: 44.9

Surface wetting as per EN 24,920 at 200 C

Spray rating ≥ 4 (Spray test for Outer shell)

5

ISO 5077 Cleaning-shrinkage resistance

Dimension Change ≤±3%

Weft wise: -0.6% Warp wise: −1.0%

ISO 6530:2005 Liquid–Chemical Penetration

Shall give greater than 80% run-off and no penetration to the innermost surface, i.e.„ Penetration = 0% and Repellency > 80% Resistanceto Penetration: 1. 30% Sulfuric acid 2. 100% o-xylene

With 30% Sulfuric acid – Penetration- 0% – Repellency- 95.8% With 100% o-xylene – Penetration- 0% – Repellency- 96.6%

(continued)

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M. S. Parmar and N. Sisodia

Table 4 (continued) Properties

Requirement

Test Results

Water-penetration resistance as per EN 20,811

Shall not show the appearance of water drops

No water penetration

Water–vapor resistance as per ISO 11092

Ret ≤ 30 m2 Pa/W

27.6987 m2 Pa/W

Fig. 1 Picture of complete firefighter suit developed by NITRA

4 Conclusion As a lightweight firefighter suit is always preferred, and due to this reason, a lightweight outer layer coded as L1 (166 g/m2 ) is selected out of three developed fabric samples for the outer layer. Twelve samples (coded as T1 to T12) of thermal layers were studied for various FR and thermal properties. Four layers were taken for further study as this passed all the requirements. Out of four thermal layers, T8 (432 g/m2 ), T9 (537 g/m2 ), and T11 (347 g/m2 ) are having high mass compared to T10 (225 g/m2 ). Therefore, the T10 thermal layer was taken for further study. FR viscose fabric was selected for liner fabric as it is more comfortable than others. It is coded as ‘Lf’. The liner fabric was after 5 washes for FR property as per ISO 15025 Procedure A. In both the cases, the sample meets the requirement of IS 16890/EN 469. The thickness of the fabric was found to be 0.45 mm and tensile strength warps wise 638 N and weft wise 593 N. The tear strength of the fabric was found to be 29 N in both directions.

Light-Weight Indigenously Developed Firefighter Suit

11

All the layers (L1, T10, and Lf) were combined and tested for all the properties as per IS 16890/EN 469. From the results, it is clear that combined layers meet the requirements of IS 16890/EN 469. A two-piece garment (coat and trousers) easy to put on and easy to remove was developed at M/s Aeronav Industrial Safety Appliances, NOIDA. The total weight of a large-size two-piece firefighter suit was 3 kg. Acknowledgements The authors of this paper express their deep sense of gratitude to the Ministry of Textiles, Govt. of India for sponsoring this work.

References 1. Coca A, Williams WJ, Roberge RJ, Powell JB (2010) Effects of firefighter protective ensemble on mobility and performance. Appl Ergon 636–641 (2010) 2. Zhang H, Song G, Ren H, Cao J (2018) The effects of moisture on the thermal protective performance of firefighter protective clothing under medium intensity radiant exposure. Textile Res J 88(8):847–862 3. Barker RL, Guerth-Schacher C, Grimes RV, Hamouda H (2006) Effect of moisture on the thermal protective performance of firefighter protective clothing in low-level radiant heat exposures. Textile Res J 76(1):27–31 4. Fanglong Z, Weiyuan Z, Minzhi C (2007) Investigation of material combinations for firefighter’s protective clothing on radiant protective and heat-moisture transfer performance. Fibres Textiles Eastern Europe 15(1), article 72 5. Selkirk G, McLellan TM (2004) Physical work limits for toronto fire-fighters in warm environments. J Occupat Environ Hygiene 1(4):199–212 6. Shaw A (2013) Selection of flame resistant protective clothing. In: Handbook of fire resistant textiles, pp 351–363, Woodhead (2013) 7. Jiang D, Sun C, Zhou Y et al (2015) Enhanced flame retardancy of cotton fabrics with a novel intumescent flame-retardant finishing system. Fibers Polymers 16(2):388–396 8. Hofmann K, Wartig A, Thomann R, Dittrich B, Schartel B, Mülhaupt R (2013) Functionalized graphene and carbon materials as additives for melt-extruded flame retardant polypropylene. Macromolecular Mater Eng 298(12):1322–1334 9. Mao N (2014) High performance textiles for protective clothing. In: High performance textiles and their applications, chapter 3, 91–143, Elsevier 10. Shishoo R (2002) Recent developments in materials for use in protective clothing. Int J Clothing Sci Technol 14(3–4):201–215 11. Effect of Para-Aramid on Performance of Firefighting Clothing. (n.d.). last accessed 2022/08/15, http://www.dupont.co.uk/products-and-services/personal-protective-equipment/ thermal-protective-apparel-accessories/articles/nomex-firefighting-clothing.html 12. Boorady LM, Barker J, Lee Y-A, Lin S-H, Cho E, Ashdon SP (2013) Exploration of firefighter turnout gear; Part 1: identifying male firefighter use needs. J Textile Apparel Technol Manag 8(1):1–13 13. Adams PS, Keyserling WM (1993) Three methods for measuring range of motion while wearing protective clothing: a comparative study. Int J Indus Ergon 12(3):177–191

Developing Functionality in Geriatric Wear Through Designing Monisha Singh and Sangita Srivastava

Abstract In India, the size of the geriatric population i.e., persons above the age of 60 years is growing rapidly. According to a census study by the government of India in 2013, the population of senior citizens in India is currently the second largest in the world. In the surveys published by the United Nations, the Indian geriatric population is expected to rise, from approximately 198 million in 2020 to approximately 326 million in 2050. As age advances, the body undergoes many changes, most of which are degenerative and the elderly may suffer from one or more chronic diseases. These changes affect the clothing requirement of the elderly and their interest in clothing. A common problem in the majority of elderly people is their negative concept of special clothing. Therefore, unless the clothing is well designed, attractive, and not different in appearance from current styles, the elderly feel that it emphasizes rather than minimizes their poor features. Two upper torso and two lower torso garments for elderly women were designed and developed in order to boost the spirit of independence. Functional clothing was designed in such a way that they have a minimum inhibitory effect on movements and provide maximum comfort and performance to elderly women. These functional clothing items were assessed by the elderly and their caregivers in attributes like the ease of donning and doffing, ease in the manipulation of fasteners, aesthetics, functionality and comfort. These functional clothing items were found highly suitable in terms of all attributes, found user-friendly, and helped elderly women to cope with their physical restrictions and at the same time provide them with beautiful clothing of their own choice. Keywords Ageing · Functional clothing · Designing · Geriatric

M. Singh (B) · S. Srivastava Faculty of Science, Department of Family and Community Sciences, University of Allahabad, Prayagraj, Uttar Pradesh, India e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024 D. Gupta et al. (eds.), Functional Textiles and Clothing 2023, Springer Proceedings in Materials 42, https://doi.org/10.1007/978-981-99-9983-5_2

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1 Introduction Ageing can be defined as a progressive functional decline, or a gradual deterioration of physiological function with age, including a decrease in productiveness [1], or the intrinsic, inevitable, and irreversible age-related process of loss of viability and increase in vulnerability [2]. The population of elderly persons has increased substantially over the years. Currently, the growth rate of the number of older individuals is three times higher than the total population as a whole [3]. Their population has shown a steady rise, 5.1% in 1901, 5.6% in 1961 6.8% in 1991, and 8.9% in 2016 and expected to be 21% in 2050 [4]. Within a span of 100 years, the percentage of elderly in India is expected to increase by four times, from 5.4% in 1950 to 20.2% in 2050 [5]. India has thus acquired the label of an ‘ageing nation’ with 8.9% of its population being more than 60 years of age. As the age increases, the body undergoes many physiological and psychological changes. These changes occur at a very rapid rate in older age and most of them are degenerative in nature. Due to various physiological changes, it becomes difficult for the elderly to dress and perform personal daily activities [6]. Primarily, they lose their ease in dressing which makes getting dressed difficult for them. Most of the elderly suffer from diseases which lead to restrictive movement or loss of function which requires the use of functional clothing that can make body movements like donning, doffing, walking, and arm and leg movements painless and comfortable. Clothing for the elderly must help to make them independent as much as possible. It should be adapted in such a way that clothing becomes easier for both, the elderly and the caregiver. Aesthetically, clothing can serve three major functions for the elderly: call attention to one’s good features, camouflage poor features and give a psychological uplift. Both aesthetic and functional features are required for elderly persons. The aesthetic features are required for psychological satisfaction while functionalized designs are required for allowing more independence in donning and doffing the clothes. Thus, there is a need for clothing that functions as per the needs of the elderly which allows them to feel like they fit in with their social group reducing the stigma they may face on a daily basis. To overcome these problems, this study was aimed at designing suitable and functional clothing for elderly women.

2 Methodology Design is a critical component in the development of clothing. The process of designing a range of functional clothing begins and ends with user-specific requirements. These requirements are determined by the environment in which the user lives, the activities they have to perform and also studying hindrances caused by available clothing in performing daily activities. After analyzing the results obtained, examining the recorded observations, and studying the collected reviews on health problems, clothing problems and clothing preferences, clothing problems caused by

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the diseases from which the elderly were affected were enlisted. Keeping the problems and needs of the elderly and desired effect of functional clothing in mind, two different upper and two lower torso garments for elderly women were designed. Designs include consideration about changing body dimensions; limitations of strength and mobility as well as physiological and social needs. To overcome these difficulties, the designs were created by adaptations, proper placement of openings and usage of suitable fasteners according to their specific needs. Computer-aided designing was used to design all functional clothing. Fashion CAD software was used in order to visualize the functional clothing in three dimensions before construction. The study was limited to summer clothing for elderly women only. Drafting was used for the construction of the pattern. Drafting conforms to standard measurements. Standardized size charts for women available online by different clothing brands were used for this selection. The size M for women was used for pattern construction. The final prototypes were developed using the patterns. An analysis of developed functional prototypes was done. Garments were provided to the elderly population and their caregivers. They were asked to evaluate garments on the basis of (a) ease in donning and doffing, (b) ease in the manipulation of fasteners, (c) aesthetics, (d) functionality and (e) comfort on a self-structured schedule. Three different scores were given—3 for highly suitable (HS), 2 for suitable (S) and 1 for somewhat suitable (SS). Weighted mean scores (W.M.S.) were calculated from the number of respondents against each characteristic of functional features. Finally, W.M.S. were analyzed (Eq. 1) for suitability level as in the following ranges: Highly suitable (H S): 2.34–3.00***, Suitable(S): 1.67–2.33**, Somewhat Suitable (SWS)0.00–1.66*. W.M.S =

No of respondent × 3(HS) + No of respondent × 2(S) + No of respondent × 1 (SWS)

(1)

2.1 A Side Open Kurti The adaptation of the basic kurti was done into a side open kurti. The kurti was designed to provide independent and painless donning and doffing. This design was open from the side seam on one side and one side shoulder with Velcro and snap button closure for easy access to donning and doffing (Figs. 1 and 2). Velcro and snap button closures were used as they were easy to manipulate by the elderly. This design was incorporated with a pocket on the other side seam, as keeping their belongings near them creates a sense of security. The design of the kurti was kept such that no raising of the hand above the head is required for donning and doffing. These features make this design suitable for women having mobility problems, suffering from frozen shoulders, or poor body balance or if they are bedridden. A keen interest was taken to enhance the aesthetics of the kurti by using embroideries at the neck and lower panel. A combination of printed and plain fabric of cotton adds comfort and aesthetics to the garment.

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Fig. 1 Views of the kurti a Front b Side c Side closure d Top closure

2.2 A Three-Piece Princess Line Kurti The adaptation of basic kurti was done to a three-piece princess line kurti. The kurti was designed for elderly women having mobility problems. The kurti was detachable in three pieces, two side pieces from the princess line having one sleeve and front and back bodice attached and one piece in the center back and front attached through the neck (Figs. 3 and 4). These pieces were attached with velcro closure from front to back on both sides. This feature provides ease in donning and doffing as no raising of the hand above the head and no hand movement is required. Velcro closures on panels from one end to another increase ease of manipulation of fasteners. Cap sleeves were used to add comfort as they are loose and short in length. Square neck and machine embroidery on the middle panel of the kurti was used for increasing the aesthetics of the garment. A nice colour combination of olive green and maroon was used for improving the overall look of the garment.

2.3 Side Open Salwar The adaptation of the basic salwar was done to a side open salwar. The salwar was designed with elasticised back at the waist and a belt with Velcro closure on the front to adhere to changing waist dimensions. Velcro closure is easy to manipulate as tying of string becomes difficult as age progresses due to a lack of hand and eye coordination (Figs. 5 and 6). A concealed pocket at the front belt was used in order

Developing Functionality in Geriatric Wear Through Designing

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Fig. 2 Drafting of side open kurti

to create a sense of security among elderly women as they can keep their special belongings near them. Incontinence is a major problem in old age, so diapers or lower garment has to be changed frequently, but with poor body balancing, stiff joints and mobility disorders this becomes a difficult task for both the elderly and their caregivers. To combat this problem effectively, a whole side opening from one end to another end on both legs was used with zipper closures which were easy to manipulate and divide the salwar into two pieces- the front and the back. This facilitates easy donning and doffing. Black-coloured fabric was used as it does not get soiled easily..

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Fig. 3 Three-piece princess line kurti a Front view b Side view c Front closure

2.4 A Kunda Open Salwar The adaptation of basic salwar was done to a kunda open salwar. This adaptation has an elasticized waist at the back and a belt at the front with Velcro closure to adhere to the ever-changing waist sizes of the elderly (Figs. 7 and 8). In old age, poor eyesight and poor hand–eye coordination are major problems, due to which tying of string becomes a major problem for the elderly. The usage of Velcro closure helps in combating this problem. A concealed pocket was used on the front belt. The elderly can use this pocket to keep their belongings which will create a secure feeling among them. This salwar is open on the kunda side from the end of one leg to the end of another leg with a zipper closure. Incontinence is a common problem of old age, which requires frequent changing of diapers or of lower garments. This opening facilitates easy change of diapers, cleaning of body parts, easy management of catheters etc. This opening also facilitates easy donning and doffing and can be done in minimal time, especially in bedridden patients.

3 Results and Discussion The researcher visited the Samarpan Old age home, Aastha health resort, old age home and Lilawati old age home in Lucknow and various homes at Allahabad, Ballia and Varanasi for evaluation of developed prototypes of functional clothing for elderly. The evaluation was done firstly by interview and then followed by wear trials on 165 elderly women. The elderly, their family members and caregivers were asked to rate the prototypes, Table 1. The basis on which evaluation was done were (a) ease

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Fig. 4 Drafting of three-piece princess line kurti

in donning and doffing, (b) ease in the manipulation of fasteners, (c) aesthetics, (d) functionality and (e) comfort on a self-structured schedule. The elderly were very happy to see the dresses, especially the elderly residing at old age homes. They gave a very positive response. The caregivers were equally happy as they were stressed because donning and doffing elderly persons was a tiring and hectic task for them. Some elderly women refused to agree to trials due to mood swings. Some of them did wear trials and responded but were not ready for a photograph, while few of them eagerly participated in the wear trials and the researcher collected feedback from them and the caregivers (Table 2).

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Fig. 5 Views of the salwar a Front b Left Side c Right Side d Closed view

4 Conclusions Clothing is one of the basic needs of human beings after food and shelter. It is an appearance construction tool as well as provides psychological support. The anatomical, physiological, psychological and social changes in old age affect clothing requirements. But the market lacks clothing which caters to the need of the geriatric population. The common problems identified in available clothing are, (a) difficulties in manipulating fasteners due to lack of eye-hand coordination, (b) fastening and unfastening of placket and cuffs due to lack of strength in hands and poor vision, (c) setting lower garments at the waist due to loss of muscles and poor body balancing, (d) fastening of pants belt and fly’s zipper, (e) tying/untying of string, (f) slipping legs in garments and removing them, (g) problems in raising and stretching arms, stretching of legs and bending of knees, (h) poor balance in the standing position and (i) a lot of time in donning and doffing. The developed prototypes were evaluated by the elderly, their family members, their caregivers and some subject experts. All the newly constructed functional clothing was found highly suitable in all attributes namely, ease in donning and doffing, ease in manipulation of fasteners, aesthetics, comfort and functionality.

Developing Functionality in Geriatric Wear Through Designing

Fig. 6 Drafting of Salwar

21

22 Fig. 7 Views of Kunda salwar a Front b Back

Fig. 8 Drafting of kunda open salwar

M. Singh and S. Srivastava

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Fig. 8 (continued)

Table 1 Comparison of side open kurti and three-piece kurti on different attributes

Table 2 Comparison of Side open Salwar and Kunda open Salwar on different attributes

Attributes

W.M.S Kurta1

Kurta2

Ease in donning

2.80

2.98

Manipulation of fasteners

2.58

2.16

Aesthetics

2.94

2.80

Functionality

2.76

2.90

Comfort

3

2.89

Ease in doffing

2.80

2.98

Attributes

K1

K2

Ease in donning

2.94

2.94

Manipulation of fasteners

2.30

2.50

Aesthetics

2.12

2.20

Functionality

2.98

2.98

Comfort

2.63

2.87

Ease in doffing

2.94

2.94

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References 1. Partridge L, Mangel M (1999) Messages from mortality: the evolution of death rates in the old. Trends Ecol Evol 14:438–442 2. Benjamin B (1965) Ageing: the biology of senescence. by Alex Comfort. [pp XVI + 365 London: Routledge and Kegan Paul, 1964. Second Edition. 42s]. J Insti of Actuaries 91:224–224 3. Sathyanarayana KM, Kumar S, James KS (2014) Living arrangements of elderly in India: Policy and programmatic implications. Population Ageing in India, 74–95 4. Elderly in India (2016) Central Statistics Office, Government of India. https://mospi.gov.in/pub lication/elderly-india-2016. Accessed 10 October 2022 5. World Population Prospects- Population Division (UN): The 2019 Revision. http://esa.un.org/ unpd/wpp/index.htm. Accessed 10 October 2022 6. Çivitci S¸ (2004) An ergonomic garment design for elderly Turkish men. Appl Ergon 35:243–251

Advanced Activated Carbon Adsorbent Filter Material for Chemical Protective Clothing Himanshi Dhyani, Ravindra V. Adivarekar, Vikas B. Thakare, Suraj Bharati, Pushpendra K. Sharma, Kaveri Agrawal, Atul K. Sonkar, and Prabhat Garg

Abstract This study focuses on the development of an advanced chemical protective filter material to be used in Nuclear, Biological and Chemical (NBC) protective gears. The NBC protective clothing mainly consists of three layers- outer, middle, and inner layers. Specific features like flame retardancy, oil repellency, water repellency, and antistaticity are imparted in the outer layer, while the innermost layer, which remains close to the body consists of features providing comfort and safety. The middle layer is a filter layer made of adsorbent material. Activated Carbon Fabric (ACF) is a versatile textile material owing to its high surface area, meso and microporosity, flexibility, and ease of lamination onto various substrates. However, due to its fragility, lamination of ACF onto a substrate is recommended to provide strength to it. In the present work, a coating of poly (diallyl dimethyl ammonium chloride) (PDDA) was developed onto the ACF surface using the dip coating method to improve the tensile strength of the fabric without sacrificing its comfort and chemical properties. Polymer-coated ACF (PDDA@ACF) samples were characterized by scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, Thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller (BET) surface area analyser. Samples were tested for tensile strength and air permeability. The performance evaluation of the developed coated fabric was determined as per IS 17377 against Sulphur Mustard (HD), a chemical warfare agent. The analysis confirmed the successful introduction of PDDA onto the surface of ACF. Tensile and air-permeability test results revealed improvements in mechanical and comfort properties, respectively. A marginal reduction in BET surface area was observed which may be attributed to the presence of polymer over the structure of ACF. The chemical protection performance was found as per the requirement of NBC protective clothing (BTT > 24h).

H. Dhyani · V. B. Thakare · S. Bharati · P. K. Sharma · K. Agrawal · A. K. Sonkar · P. Garg (B) Defence Research and Development Establishment, Jhansi Road, Gwalior 474002, India e-mail: [email protected] H. Dhyani · R. V. Adivarekar Institute of Chemical Technology, N P Marg, Matunga (e), Mumbai 400019, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024 D. Gupta et al. (eds.), Functional Textiles and Clothing 2023, Springer Proceedings in Materials 42, https://doi.org/10.1007/978-981-99-9983-5_3

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Keywords NBC protective clothing · Activated carbon fabric · Chemical warfare agents

1 Introduction In a nuclear, biological, and chemical scenario, protective clothing is obligatory for the safety of first responders, defence personnel, and civilians [1–8]. NBC protective clothing is designed to protect against exposure to hazardous chemicals and acts as a physical barrier between the wearer and the hazardous material, preventing it from coming into contact with the skin [1, 8, 9]. The general construction of NBC protective clothing is schematically described in Fig. 1, which consists of three main layers: aramid fabric used in the outer layer with flame retardant, oil repellent, water repellent, and anti-stat features; cotton fabric used in the innermost layer; activated carbon adsorbent with polypropylene non-woven support in the middle layer. This clothing protects the wearer against toxic chemicals repelling it by the first layer and adsorbing it on the middle activated carbon porous layer [6, 10, 11]. From ancient times to recent times, activated carbon has been the most widely used adsorbent material for protection against super-toxic chemical warfare agents (CWAs) [6, 7, 10–16]. The CWAs are chemicals with the main categories of nerve agents (which destroy the central nervous system), blister agents (which create blisters on the skin), choking agents (which cause sensorial irritation and inflammation of the nose and lung tissues), and blood agents (which prevent oxygen circulation from the blood to the cells) [6, 16, 17]. For protection against these toxic chemicals, activated carbons are used in one of the different forms, e.g., charcoal, spheres, or fabric bonded with textiles, e.g., nonwoven polypropylene, as support [6, 10, 12, 18].

Fig. 1 Construction of NBC protective clothing material

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Activated carbon fabric (ACF) is developed from precursors such as polyacrylonitrile (PAN), cellulose, pitch, and phenolic resin in three steps: thermal stabilization, carbonization, and physical or chemical activation [19–24]. ACF consists of various features like high surface area, lightweight, uniformity, flexibility, and ease of functionalization that make it advantageous over previously used activated carbon-based technologies, e.g., activated carbon charcoal and spheres. In addition, the desired combination of mesoporosity and microporosity, which is directly available on the ACF surface, provides excellent morphology for entrapping toxic contaminants available in both gas and liquid forms [19, 21]. Despite having these features, ACF is not so popular for protective gear, especially against CWAs, due to its fragile nature. Though it is used as an adsorbent layer for protective clothing along with support from other textile materials, the weight penalty to the wearer increases. This also limits physiological comfort levels owing to decreased air and moisture permeability, especially when in use for a longer duration. One solution to this issue could be the enhancement of the carbonization time of precursor fabric during the development of ACF, but at the same time it would limit the generation of pores on the surface and hence the protection level [6, 19]. Among established state-of-the-art methods for strengthening fragile substrates, fixing the fragile substrates within a cage of high-strength material is the most common procedure. Coating ACF with a polymer material also imparts strength to it. However, coating with a polymer solution may also drastically deteriorate its protective features by blocking the openings of pores available on the surface of ACF or reducing the volume by penetrating and coating the walls of the pores. The present studies are aimed at developing an advanced ACF-based protective filter material to be used in NBC protective clothing using a coating of a suitable material to increase its strength with minimum loss of protection efficiency and moisture permeability. For this purpose, a solution of coating material Poly (diallyldimethylammonium chloride) (PDDA), average Mw 100,000–200,000 (low molecular weight), 20% wt. in water was selected owing to its unique properties and ease of coating procedure on activated carbon fabric surface to realize its potential as a strong adsorbent material. PDDA is a positively charged water-soluble polyelectrolyte and can bind with negatively charged activated carbon fabric through electrostatic attraction [25, 26]. The chemical structure of the PDDA polymer is shown in Fig. 2. The dilution of the polymer was optimized for a sufficient coating of ACF to provide improved strength with the desired protection efficiency and comfort. The developed PDDA-coated ACF (PDDA@ACF) was analysed for its mechanical properties, comfort properties (in terms of air- permeability), and chemical protection properties against sulphur mustard–a potential skin-penetrating CWA from the blistering agent’s class (Fig. 3).

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Fig. 2 Molecular structure of poly (diallyldimethylammonium chloride (PDDA)

H3C

CH3

N+ H3C

Cl-

CH3

n

S

Fig. 3 Molecular structure of sulphur mustard (HD)

Cl

Cl

bis(2-chloroethyl) sulfide 2 Experimental 2.1 Materials and Chemical Reagents Woven activated carbon fabric (ACF) was obtained from Taiwan Carbon Technology, Taiwan, and used as received. Aramid fabric (Arvind Mill Limited, Gandhinagar), polypropylene (PP) non-woven (Melange Polymer Private Limited, India), and cotton fabric (Bannari Amman Spinning Mill Limited, India) were used as received. The details of ACF, aramid fabric, PP non-woven fabric, and cotton fabric (Fig. 4) are mentioned in Table 1. Poly (diallyldimethylammonium chloride) (20 wt. % aqueous solution) was obtained from Sigma-Aldrich, USA, and used as received. Sulphur mustard (HD) was synthesized in-house as per reported literature by the Organisation for the Prohibition of Chemical Weapons (OPCW)-declared schedule I facility at the Defence Research & Development Establishment (DRDE), Defence Research & Development Organization (DRDO), Gwalior, India [27].

(a)

(b)

(c)

(d)

Fig. 4 Different layers of a conventional NBC protective clothing material a Outer fabric b nonwoven fabric c Activated carbon fabric d Inner layer

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Table 1 Parameters of different fabric layers of NBC protective clothing Parameters

Activated carbon fabric

Cotton fabric

Aramid fabric

Polypropylene non-woven fabric

Areal density (g/ m2 )

137

120

117

45

Thickness (mm)

0.52

0.38

0.26

0.30

Weave

1/1 plain weave

Single jersey

1/1 plain weave

Spun bond

Ends/inch

44

20

58

–

Pick/inch

31

18

45

–

Table 2 Details of samples Samples details

Concentration of polymer solution % (v/v)

Add on polymer % (w/w)

ACF

–

–

ACF_0.1 P

0.10

2.59

ACF_0.25 P

0.25

10.08

ACF_0.50 P

0.50

15.19

2.2 Preparation of the Activated Carbon Fabric (ACF) Coated with PDDA (PDDA@ACF) An aqueous solution of PDDA polymer in different concentrations (0.1%, 0.25%, and 0.50% v/v) was prepared by diluting the polymer solution with the required quantity of distilled water. For the purposes of coating, a 25 cm × 18 cm ACF piece was dipped into the corresponding 150 mL dilute polymer solution and kept overnight (18h approx.) in a glass tray at room temperature. The next day, coated ACF was further dried in the oven at 150°C for 1h, followed by high vacuum drying for half an hour at the same temperature. Table 2 depicts the amount of polymer expressed in a percentage as calculated from the weight difference between ACF and polymer-coated ACF.

2.3 Material Characterization Investigations of polymer-coated ACF samples vis-à-vis control ACF samples were carried out using scanning electron microscopy (SEM, Carl Zeiss EVO 15 LVSM, Germany), Fourier transform infrared (FTIR) spectroscopy (ALPHA II, Bruker, USA), thermogravimetric analyzer (TA Instrument, Hi 2950) and Brunauer– Emmett–Teller (BET) surface area (ASAP 2020 system, Micromeritics, Norcross, USA).

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Tensile properties, i.e., breaking strength (Kgf) and elongation (%) of samples, were evaluated using Tensile Testing Machine (Divyanshi Engineering Services, India) at a testing speed of 100 mm/min with a gauge length of 170 mm. Air-permeability (cm3 /cm2 /sec) values of samples were determined on a Gas Permeability Analyzer (M19 Lab, USA) using standard ASTM D737.

2.4 Performance Evaluation Developed PDDA@ACF fabrics were tested as per Indian Standard 17,377 (Part 1: 2020) Textiles–nuclear biological chemical (NBC) permeable protective clothing Part 1 Qualitative method of determining breakthrough time on exposure to chemical warfare agent–sulphur mustard (HD), a potential Blistering Agent.

3 Results and Discussion 3.1 FTIR Studies FTIR spectra were used to confirm the post-coating presence of PDDA over the surface of ACF by determining the chemical functional groups. The infrared spectra of ACF and ACF with different concentrations of PDDA polymer (0.1% to 0.50%) are shown in Fig. 5. The peaks observed at 2948 cm−1 and 2879 cm−1 in all the samples were due to the stretching vibration of -CH from ACF. The peak at 1636 cm−1 is caused by the bending vibration of C-N present in PDDA [28, 29]. The peak at 1472 cm−1 is caused by the bending vibration of –CH2 from PDDA [29]. Therefore, these FTIR results confirmed the successful incorporation of PDDA with the ACF.

3.2 Surface Morphology Scanning electron microscopy (SEM) images employed to observe the surface morphologies of ACF after coating with different concentrations of PDDA polymer (0.1% to 0.50%) are shown in Fig. 6. Morphological studies reveal a uniform, thin polymer coating on the fibers of ACF. The appearance of lustre at the edge of the yarn is observed after coating with PDDA polymer on activated carbon fabric. No cracks or damage to the coating or to the fabric were visible.

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Fig. 5 FTIR spectrum of various samples of ACF and PDDA@ACF

ACF

ACF_0.1 P

ACF_0.25 P

ACF_0.50 P

Fig. 6 SEM pictures of ACF with different PPDA polymer concentrations (0.1% to 0.50%)

3.3 Thermal Analysis The information regarding the thermal stability of developed polymer-coated ACF (PDDA@ACF) fabrics was further obtained by thermogravimetric analysis (TGA). Figure 7 shows the thermal decomposition profiles of pristine ACF, pristine polymer, and different PDDA@ACF in the air. The degradation profiles were recorded from 25 °C to 800 °C at a heating rate of 10 °C min−1 . The pristine polymer showed a trend similar to ACF and PDDA@ACF up to 350 °C followed by sharp weight loss, while pristine ACF, as well as all coated ACF specimens, showed a three-step weight loss: (i) evaporation of moisture entrapped within the pores until 120 °C; (ii) gradual decomposition of polymer beyond 120 °C (regions 1 and 2); (iii) sharp decomposition beyond 550 °C (region 3). Occurring at 660 °C, almost no residual ACF or polymer remained for PDDA@ACF [30]. PDDA@ACF (ACF_0.50P) exhibited faster growth from 120 °C to 550 °C (region 2) compared to other samples owing to a higher content

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Fig. 7 TGA curves of ACF and ACF with different PPDA concentrations (0.1% to 0.50%)

of polymer (15.19% w/w). It is evident from the data that the PDDA@ACF filter layer is thermally stable within the working range of temperature under normal conditions.

3.4 BET Surface Area Nitrogen (N2 ) adsorption–desorption isotherms were measured at −196 °C using ASAP 2020 (Micromeritics). The ACF and PDDA@ACF samples were degassed using a continuous vacuum at 200 °C for 500 min before analysis. The adsorption isotherms were used to calculate the BET surface area. From Table 3, it is observed that PDDA coating on ACF surfaces affects the surface area of ACF, resulting in a marginal decrease of 3.34% to 8.43% on an increment of polymer coating from 2.59% to 15.19%. Table 3 BET surface area details of uncoated/polymer-coated ACF Samples Details

Polymer add-on (%)

BET Surface Area (m2 /g)

ACF

–

945.64

ACF_0.1 P

2.59

914

ACF_0.25 P

10.08

883.14

ACF_0.50 P

15.19

865.84

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33

3.5 Tensile Strength Tensile properties, i.e., breaking strength (Kgf) and elongation (%) of ACF coated with different content of PDDA polymer samples, were determined as per IS 1969. The average values of three specimens from each sample tested in the warp direction are summarized in Table 4. Breaking strength was found to be increasing from 30.58% to 50.00% upon an increment of polymer coating from 2.59% to 15.19%, Fig. 8. This significant improvement in mechanical properties of PDDA@ACF samples could be achieved due to the formation of a continuous, strong, thin cylindrical layer of PDDA polymer covering activated carbon yarn completely and the filling of PDDA polymer within the interstices of the fibre–fibre regions of the activated carbon yarn [31]. The statistical 2-sample t-test was employed to study the effect of polymer content on the tensile properties of ACF. Significant improvement in breaking strength (Kgf), as well as elongation % of ACF, was observed after coating with different content of PDDA polymer (2.59% to 15.19%). A non-significant reduction in breaking strength, as well as elongation % of ACF coated with 15.19% polymer, was observed in comparison to ACF coated with 10.08% polymer. No further improvements in tensile properties are recorded beyond a 10.08% polymer coating. Table 4 Tensile properties of uncoated/polymer-coated ACF in warp direction Samples details

Polymer add-on (%)

Breaking strength (Kgf)

Elongation (%)

ACF

–

12.33

9.44

ACF_0.1 P

2.59

15.66

11.48

ACF_0.25 P

10.08

18.66

12.68

ACF_0.50 P

15.19

18.00

11.68

22 20 18 16

Breaking strength (Kgf)

14

Elongation %

12 10 8 ACF

ACF_0.1P

ACF_0.25P

ACF_0.50P

Fig. 8 Tensile strength properties of ACF with different PPDA polymer concentrations

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H. Dhyani et al.

3.6 Air-Permeability It is a well-established fact that coating a porous material limits its permeable properties in a significant manner. The air-permeability parameter of a fabric is an indicator of comfort and physiological strain. Air-permeability properties of ACF coated with different contents of PDDA polymer (2.59% to 15.19%) (PDDA@ACF) samples were determined as per ASTM D737 by applying a pressure drop of 125 Pa across a 20 cm2 area of samples. The average values of three specimens from each sample are summarized in Table 5. Interestingly, in the present case, air-permeability properties were found to be increasing from 18.19% to 51.29% upon an increment in polymer content from 2.59% to 15.19% (Fig. 9). The 2-sample t-test employed as the statistical tool to study the effect of polymer coating percentage on air-permeability of ACF confirms the significant improvement in air-permeability properties of ACF after coating with different content of polymer (2.59% to 15.19%). A significant improvement in air-permeability of PDDA@ACF could be explained in terms of a higher space volume among intersections of warp and weft yarns after coating with polymer, which was further confirmed by analysing the samples using a Leica microscope (Fig. 10). From the images, it is well evident that owing to the fine Table 5 Air-permeability values of uncoated/polymer-coated ACF Air-permeability (cm3 /cm2 /s)

Samples Details

Polymer add-on (%)

ACF

–

74.96

ACF_0.1 P

2.59

88.60

ACF_0.25 P

10.08

104.25

ACF_0.50 P

15.19

113.41

115 105 95 Air-permeability (cm3/cm2/sec)

85 75

65 ACF

ACF_0.1P

ACF_0.25P

ACF_0.50P

Fig. 9 Air-permeability values of ACF with different PPDA polymer concentrations (0.1% to 0.50%)

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35

Fig. 10 Microscopic images of ACF with different PPDA polymer concentrations (0.1% to 0.50%)

coating of polymer onto the fibres of ACF, interstitial spaces are created between the fibres, and this space is increased upon increasing the content of the coating.

3.7 Performance Evaluation of ACF@PDDA Against Sulphur Mustard (HD): A CWA The chemical protection performance of ACF with different contents of PDDA polymer (2.59% to 15.19%) (PDDA@ACF) was evaluated by performing the HD CWA Breakthrough Test as per IS 17377:2020. This qualitative test examines the penetration of CWA sulphur mustard through fabric layers in terms of time duration. A brief procedure for performing the HD-BTT test has been described here. A 38 mm diameter white cotton drill is placed onto a 50 mm diameter circular brass plate and retained by a 1 mm thick flanged brass ring (spacer ring) with a 53 mm internal diameter at the flange and a hole of 19 mm diameter in the centre. The purpose of this flanged brass ring is to retain the white cotton drill on the 50-mm-diameter circular brass plate. 12 µL of sulphur mustard in the form of drops was dispensed onto the white cotton drill exposed in the 19 mm hole using a micropipette. This system provides a standard concentration of mustard gas vapours generated between the spaces above the cotton drill. The assembly is temporarily covered with a glass disc kept in a fuming cupboard maintained at 20 ± 1 °C for 30 min. Meanwhile, two layers of the test specimen, with the innermost layers facing together, were placed

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onto a glass disc. On the top of the test specimen, a disc of detector paper (prepared by dipping Whatman filter paper into 0.05% solution of Congo Red dye, drying and spotting SD reagent 2,4 dichlorophenol benzoyl chloroimide) was placed. After a 30-min period for temperature and vapour equilibrium, the glass disc is removed, and the test specimens with the detector paper disc uppermost are laid onto the spacer ring. The sample specimen and detector paper were further retained in place by means of a 41-mm-thick flanged brass ring with a 57-mm internal diameter at the flange and a 32-mm hole in the centre. Finally, a clean, plain glass plate was placed on top of the second flanged brass ring, and the assembly was left undisturbed throughout the period of the test. The detector paper is examined through the glass plate at regular intervals to identify the moment of formation of the blue spots. The mustard gas penetration time (HD Breakthrough Time) is taken as the interval in hours between laying the test specimen on the spacer ring and the first indication of the appearance of the blue spots [6, 10, 32]. Two sets of specimens were evaluated as per the above-mentioned HD-BTT test, as explained. One set was from the specimen having a non-coated ACF layer along with the support of a PP nonwoven layer and outer as well as inner layers (specimen 1 as per conventional configuration, Fig. 11a), and the second set belonged to the specimens having an ACF@PDDA layer without a PP nonwoven layer (specimen 2 as per developed configuration, Fig. 11b). The specimens were evaluated in triplicate for a period of 24 h, and the criteria for qualifying the specimen (HD-BTT > 24 h) were followed as per IS 17377:2020. The results for both categories of specimens are compiled in Table 6.

(a)

(b)

Fig. 11 Exploded view of test specimens. a Uncoated ACF with support of non-woven, outer and inner fabric, b polymer coated ACF with support of outer and inner fabric

Table 6 HD-BTT test results Test-specimens set Configuration

HD-BTT (Hrs.-min.) Remarks

1

Outer + ACF + Non-woven + Inner >24 h

Qualified

2a

Outer + ACF_0.1 P + Inner

>24 h

Qualified

2b

Outer + ACF_0.25 P + Inner

−4) [31]. The ratio method to categorize women’s bodies derives numeric parameters using ratios of key bodily measurements [34]. Along similar lines, Hsu categorizes young Taiwanese females using the bust-to-waist ratio (B/W Ratio) into four classes. Based on variation in B/W Ratios, the shape categories were defined as small bust with a B/W ratio ≤ 1.1, Medium bust with B/W ratio = 1.2, Full bust with B/W ratio = 1.3, and large bust with ≥ 1.4 [30]. PCA and cluster analysis. Most studies use statistical approaches like Principal Component Analysis (PCA) for data reduction and cluster analysis to define body

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types. Cluster analysis is an exploratory data analysis technique used to segment a population into homogenous subgroups. In other words, each person in a group shares similar physical traits with each other but at the same time differs from other group members [8]. Researchers use drops, arcs, and angles of key body landmarks to get an accurate idea of body shapes to run PCA and cluster analysis. Song et al. categorized the lower body shapes of adult females (18–35 years) using PCA and cluster analysis. A total of 14 drops, 6 widths, and buttocks angle were used as input variables for PCA, and further calculated principal components were used to segregate samples into three body shapes named curvy, hip tilt, and straight shapes using cluster analysis [35]. Another work by Song et al. in similar lines, wherein women’s (40–69 years) upper bodies and their posture changes were analyzed. PCA technique with Varimax rotation was used to reduce seven vertical lengths, two widths, 19 angles, and 11 depths into eight principal components. Further, a K-means cluster analysis was conducted using PC scores as independent variables to divide 423 scans into 4 cluster models [36]. Shin and Saeidi analyzed body shapes of US-based overweight and obese women and extracted 13 variables (drops, buttocks angle, bust front depth and bust back depth) through multiple PCA analyses. The five PCs were selected for cluster analysis using the K-means cluster [33]. Female Figure Identification Technique (FFIT) for Apparel©. Simmons et al. developed a software called: Female Figure Identification Technique (FFIT©) for apparel using visual basic codes derived through mathematical formulas of 6 bodily measurements (bust, waist, hip, abdomen, stomach, high hip) and the resultant nine body shapes. These body shapes include hourglass, bottom hourglass, top hourglass, spoon, rectangle, diamond, oval, triangle, and inverted triangle. These shapes were defined using some particular measurements, and the difference among shapes was discussed [37]. In their study, Lee et al. elaborated on FFIT software’s mathematical equations to compare USA and Korean women’s body types [38]. Further, Sokolowski and Bettencourt partnered with a USA-based leading apparel company to reinvestigate the 3D body scans of Size USA and modified the FFIT mathematical formulas for plus-size women [6]. Table 1 shows the FFIT software-based body shape definition, the original mathematical formula, and the modified formula for plus-size women. The shape analysis typically evaluates shapes in chronological order hourglass, spoon, diamond, bottom hourglass, top hourglass, oval, inverted triangle, triangle, and rectangle with the first shape with all requirements met being the identifier [7]. Further, Staton developed a shape-based sizing system for US plus-size women using FFIT software. The first prerequisite was to convert all the measurements into inches to create this sizing system. The data cleaning, sorting (removal of outliers), etc. was carried out. Consequently, the FFIT software’s mathematical formulas were used to classify the data into nine body shapes. Once the body shapes were identified, then the sizing system was prepared only for rectangle and spoon shapes as these shapes accommodated the majority of subjects. The data was segregated into separate Excel sheets based on shape type. The waist was used as a key determinant for the

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Table 1 FFIT software-based body type’s definition, original mathematical formulas, and the modified formulas for plus-size women Body shape

Definition [37]

Mathematical formulas Modified mathematical [38] formulas for plus size [6]

Hourglass

A small difference between hip and bust AND if the ratios of bust-to-waist and hips-to-waist were about equal and significant

If (bust-hips) ≤ 1 Then No modification If (hips-bust) < 3.6 Then If (bust-waist) ≥ 9 Or (hips-waist) ≥ 10

Bottom hourglass

Hip girth must be greater than bust girth AND if the ratios of bust-to-waist and hips-to-waist significant enough to produce a definite waistline

If (hips-bust) ≥ 3.6 And (hips-bust) < 10 Then If (hips-waist) ≥ 9 Then If (high hip/ waist) < 1.193

No modification

Top hourglass

Bust girth must be greater than hip girth AND if the ratios of bust-to-waist and hips-to-waist significant enough to produce a definite waistline

If (bust-hips) > 1 And (bust-hips) < 10 Then If (bust-waist) ≥ 9

No modification

Spoon

A large difference between hips and bust AND if bust-to-waist ratio is lower than the hourglass shape AND the high hip-to-waist ratio is high

If (hips-bust) > 2 Then No modification If (hips-waist) ≥ 7 Then If (high hip/ waist) ≥ 1.193

Rectangle

Bust and hip girths are fairly equal AND the ratios of bust-to-waist and hips-to-waist are low with no definite waistline

If (hips-bust) < 3.6 And (bust-hips) < 3.6 Then If (bust-waist) < 9 And (hips-waist) < 10

Diamond

The average of stomach, waist Not available and abdomen measurements should be greater than bust girth and have several large rolls of flesh at the mid-section

If (hip-waist) < 0, and (bust-waist) < 0

Oval

The average of stomach, waist, and abdomen measurements should be less than bust girth

Not available

If (hip-waist) < 0, and (bust-waist) ≥ 0

Triangle

Hip girth must be greater than bust girth AND if the ratio of hips-to-waist is small without having a defined waistline

If (hips-bust) ≥ 3.6 Then If (hips-waist) < 9

If (hip-bust) ≥ 3.6, then if 0 ≤ (hip-waist) < 9, or if (bust-waist) < 0, then if (hip-waist) ≥ 0

Inverted triangle

Bust girth must be greater than hip girth AND if the ratio of bust-to-waist is small without having a defined waistline

If (bust-hips) ≥ 3.6 Then If (bust-waist) < 9

If (bust-hip) ≥ 3.6, then if (bust-waist) < 9, then if (hip-waist) ≥ 0

If (hip-bust) < 3.6, and (bust-hip) < 3.6, then if 0 ≤ (bust-waist) < 9 and 0 ≤ (hip-waist) < 10

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plus size range and was also used as the base measurement when creating the sizing system. Therefore, keeping the waist as the control dimension, all the data points were arranged in ascending order. Subjects were then grouped into 2-inch intervals based on lowest to highest waist girth. The median value of waist measurement from each group was used as the suggested size. The meaning of all secondary measurements in each group became the measurement of each size within the shape-based sizing system. Lastly, the developed sizing system tested for rectangle and spoon shapes [7]. BSAS (Body Shape Assessment Scale). Connell et al. developed a set of 9 scales known as the Body Shape Assessment Scale (BSAS©). The 9 scales presented 88 choices of whole and component body parts and sizes of shapes by analyzing the front and side view of the female body. These nine scale components include body build, body shape, hip shape, shoulder slope, front torso shape, bust shape, buttocks shape, back shape, and posture. Further, each component was categorized into different subcategories based on visual analysis and expert suggestions. Body build was divided into four types: Slender, Average, Full, and Heavy; body shapes were classified as Hourglass, Pear, Rectangle, and Inverted Triangle; hip shapes were categorized into Straight, High, Mid, and Low; Shoulder Slope distributed among Square, Average, Sloped; Front torso shape divided into b, B, D type shapes; bust had three categories: Flat, Average, Prominent; Buttocks shape categories include: Flat, Average, and Prominent; Back shape was divided into Flat, High, Middle, Low; Posture was sectioned into Aligned, Forward Alignment, Compensating Alignment. Further, a software (Body Measurement Software (BMS©)) was programmed to allow body scans to be interpreted according to the BSAS© [39]. But BSAS© classification method was not adopted to classify body types to develop the sizing system, as it requires varied views of body projections and further complicates the pattern-cutting processes [35]. Morphology Clustering. Morphotype designates a specific body type based on 3D body dimensions and clustered 3D body characteristics [5]. Primarily extracting the most relevant morphologies from the sizing survey and then implementing a system to define sizing charts or virtual try-ons based on these morphological structures [40]. This technique is similar to clustering, the only difference is clustering defines body shape based on the magnitude of control measurements, and morphology clustering defines structures based on predefined morphotypes/3D shape descriptors. Morlock et al. classified German plus-size women using morphotypes. A morphotype was derived as a ratio of the body dimensions like shoulder diameter to hip diameter in frontal view and waist diameter in frontal view to shoulder diameter and hip diameter. Further, three body types were derived using these morphotypes such as A-shape, Hshape, and V-shape [5]. Hamed et al. normalized the 3D torso by removing the head and arms and using a minimal bounding sphere. Then the 3D descriptor was computed with the geodesic shape distribution for each normalized torso. Finally, through cluster analysis, geodesic shape distribution extracted the centroids of clusters, i.e., Morphotypes [40].

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The review of the literature revealed some significant observations. First, the difference among size chart development methods lies in their clustering or grouping of the data into body types. Second, the body shape analysis is a prerequisite to developing a size chart for the subjects that deviate from the standard body structure norms. Third, the success rate of a size chart majorly depends on how many more subjects it has accommodated within sizes (maximum coverage %) and how well an assigned size fits the wearer (aggregate loss) within minimum size groups. Further, in terms of body shape identification techniques, it was observed that approaches like PCA and clustering with drops, widths, buttock angle, etc., and morphology clustering required 3D body scanned data to process body shapes. Additionally, no significant literature was found in which a sizing system was developed using these shape identification techniques. All techniques are limited to shape identification and are new to developing a sizing system. Body shape classification approaches like FFIT, drop value, and ratio-based sizing systems are commonly used to derive body shapes to develop a sizing system.

3 Methodology 3.1 Questionnaire Development To filter plus-size subjects, a question was added to a questionnaire (Do you feel you are falling in plus size?). Respondents were given three options to respond to this question, including Yes/No/Maybe. The women who responded yes and maybe were allowed to proceed further to fill out the questionnaire. Additionally, women with a waist girth ≥ 34 inches and BMI ≥ 25 were taken as another identifier to segregate plus-size subjects, which Kumari and Anand coined in the Indian context [17]. Women who satisfied these two conditions were only allowed to complete the questionnaire. The selection of body dimensions, which respondents need to ask, was primarily based on the past literature on developing sizing systems. Among horizontal components, bust, waist, and hip measurements and from vertical components, height usually showed the highest factor loadings [20, 21]. Therefore, the selection of three key girths (bust, waist, and hip) and high-hip circumference (required for body shape detection), height, and weight were asked. A measurement guide per definitions given in ISO 8559, along with the simplest way of landmark detection with pictorial views (refer to Figs. 1, 2, 3, and 4), were demonstrated to the respondents. Their bodily measurements were asked as open-ended questions. Further, Cochran’s formula at a 95% confidence level was used to estimate the sample size of 384 respondents [41]. The concept of plus-size clothing is picking up fast in India, especially in Tier I cities: Delhi, Mumbai, Kolkata and Chennai [42]. Therefore, 400 respondents participated in the research from six (Delhi, Mumbai, Chennai, Hyderabad, Kolkata, and Shillong) different Indian cities; the distribution of

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Fig. 1 Bust measurement guide

respondents among cities is represented in Figs. 5 and 6 denotes the educational background of the subjects. Figures 7 and 8 represent the age group and the occupation of the plus-size subjects who participated in the study.

3.2 Method Taking the clues from the literature, three body classification methods: drop value, ratio, and modified FFIT mathematical formulas of body shape classification were applied to the complete data set, and further, the appropriateness of each approach was checked with respect to cover %, aggregate loss and a number of size charts present. To start with, the data set was divided into three height groups (a) Short: Mean-SD ( Mean + SD (>157 cm). Then each height group’s body shapes were identified using three selected methods. A constant 5 cm size interval was used to develop all three types

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Fig. 2 Waist measurement guide

Fig. 3 Hip measurement guide

of sizing systems. The group/shape with less than 2% of subjects was not accounted for in size chart development. After shape classification using three techniques, their respective size charts were prepared and validated through cover factor, aggregate loss, and number of size rolls.

Plus Size Women Body Shape Analysis: An Implication for Developing …

Fig. 4 High hip measurement guide

Fig. 5 Sample distribution among six cities

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Fig. 6 Educational background of the respondents

Fig. 7 Age group of the respondents

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Fig. 8 Occupation of the respondents

3.3 Results Descriptive statistics. Initially, the missing frequencies and outliers were checked and removed during data cleaning. A total of 400 participants’ mean, standard deviation (SD), minimum, maximum values, skewness, and kurtosis are tabulated in Table 2. All the selected measurements were normally distributed, and the statistical tests with normality assumptions can be applied to this data. In BMI terms, 63% (n = 250) of women fall in overweight (25 ≤ BMI < 30), and 37% (n = 150) of them were in the obese (BMI > 30) range. Table 2 Descriptive statistics of body dimensions (cm) Body dimensions

Mean

SD

Bust girth

102.1

5.6

Waist girth

94.9

6.2

Hip girth

106.5

6.8

High-hip girth

105.2

Height

151.0

Weight

65.9

Min

Max

Skewness

Kurtosis

89.4

118.1

0.171

−0.364

86.1

112

0.578

−0.407

91.9

129.3

0.610

0.291

6.6

91.2

126.0

0.606

0.036

5.9

134.6

170.2

0.168

0.151

8.0

48.6

96.9

0.664

0.799

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Table 3 Distribution of data (%) into body shapes and height groups using the drop value method Shape categories

Hip-bust (cm)

Very small bust

≥15

Small bust

10 to 14

2.0

Medium bust

5 to 9

6.8

Full bust

0 to 4

7.0

Large bust

(−1) to (−10)

Extra-large (inverted triangle)

>−10

Total

Short

Tall

Total

1.3

4.5

8.3

3.5

13.8

20.3

4.5

31.5

18.8

5.5

31.3

4.0

11.0

3.5

18.5

0.0

0.5

0.0

0.5

20.0

61.8

18.3

80.0

0.3

Average 3.0

3.4 Body Shape Identification: Drop Value Table 3 illustrates the distribution of data (%) into body shapes and height groups using the drop value method. Data was distributed majorly in the medium bust (31.5%) and full bust (31.3%) of plus-size women subjects in the five body shape categories. Large bust (18.5%), small bust (13.8%) and very small bust (4.5% of women were present in the category. After removing 2% or less, the bold highlighted data points show the size charts in respective height versus shape categories in Table 3. Short stature has three size charts with medium, full, and large busts; average height accommodates five size charts with very small, small, medium, full, and large busts, and in tall height group has small, medium, full, and large busts. Total data coverage was 96% of the complete data set.

3.5 Body Shape Identification: Ratio In Table 4, all the data concentrated only under the small bust (93.8%), and then medium bust (6.3%) shapes only. As usual, medium height accounts for the highest proportion of the sample among the three height groups. Then after applying more than 2% data accommodation condition, four size charts: short height with a small bust, average height with a small bust, average height with a medium bust, and tall height with a small bust, were developed with 97.3% coverage of data.

3.6 Body Shape Identification: FFIT-Modified Mathematical Formulas A visual basic-matrix analysis code (refer to Fig. 9) was developed with bust girth, waist girth, hip girth, and high-hip as a header of an Excel sheet with data in inches to identify the body shapes (Fig. 9).

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Table 4 Distribution of data (%) into body shapes and height groups using the ratio method Body shape

B/W ratio

Short

Medium

Tall

Total

Small bust

≤1.1

19.3

58.3

16.3

93.8

Medium bust

1.2

0.8

3.5

2.0

6.3

Full bust

1.3

0.0

0.0

0.0

0.0

≥1.4

0.0

0.0

0.0

0.0

20.0

61.8

18.3

100.0

Large bust Total

Private Sub BodyShapes () Dim i, j, k Dim Z1, Z2, Z3, Z4, Z5 lastrow = Cells(Rows.Count, 1).End(xlUp).Row lastcol = Cells(1, Columns.Count).End(xlToLeft).Column Dim colBust, colWaist, colHip, colHighHip As Integer For a = 1 To lastcol Step 1 If Sheet1.Cells(1, a).Value = "Bust Girth" Then colBust = a End If Next For b = 1 To lastcol Step 1 If Sheet1.Cells(1, b).Value = "Waist Girth" Then colWaist = b End If Next For c = 1 To lastcol Step 1 If Sheet1.Cells(1, c).Value = "Hip Girth" Then colHip = c End If Next For d = 1 To lastcol Step 1 If Sheet1.Cells(1, d).Value = "High Hip" Then colHighHip = d End If Next For j = 2 To lastrow Step 1 Cells(1, lastcol + 1).Value = "Bust-Hip" Cells(j, lastcol + 1).Value = Cells(j, colBust).Value - Cells(j, colHip).Value Z1 = Cells(j, lastcol + 1).Value Cells(1, lastcol + 2).Value = "Hip-Bust" Cells(j, lastcol + 2).Value = Cells(j, colHip).Value - Cells(j, colBust).Value Z2 = Cells(j, lastcol + 2).Value Cells(1, lastcol + 3).Value = "Bust-waist" Cells(j, lastcol + 3).Value = Cells(j, colBust).Value - Cells(j, colWaist).Value Z3 = Cells(j, lastcol + 3).Value Cells(1, lastcol + 4).Value = "Hip-waist" Cells(j, lastcol + 4).Value = Cells(j, colHip).Value - Cells(j, colWaist).Value Z4 = Cells(j, lastcol + 4).Value Cells(1, lastcol + 5).Value = "HighHip/Waist" Cells(j, lastcol + 5).Value = Cells(j, colHighHip).Value / Cells(j, colWaist).Value Z5 = Cells(j, lastcol + 5).Value Cells(1, lastcol + 6).Value = "Shapes" If Z2 < 3.6 And Z1 < 3.6 Then If 0 = 3.6 Then If Z3 < 9 Then If Z4 >= 0 Then Cells(j, lastcol + 6).Value = "Inverted Triangle" End If End If End If If Z4 < 0 And Z3 >= 0 Then Cells(j, lastcol + 6).Value = "oval" End If If Z1 > 1 And Z1 < 10 Then If Z3 >= 9 Then Cells(j, lastcol + 6).Value = "Top Hourglass" End If End If If Z2 >= 3.6 And Z2 < 10 Then If Z4 >= 9 Then If Z5 < 1.193 Then Cells(j, lastcol + 6).Value = "Bottom Hourglass" End If End If End If If Z4 < 0 And Z3 < 0 Then Cells(j, lastcol + 6).Value = "Diamond" End If If Z2 > 2 Then If Z4 >= 7 Then If Z5 >= 1.193 Then Cells(j, lastcol + 6).Value = "Spoon" End If End If End If If Z1 = 9 Then Cells(j, lastcol + 6).Value = "Hourglass" End If End If End If If Z4 >= 10 Then Cells(j, lastcol + 6).Value = "Hourglass" End If Next End Sub

Fig. 9 Visual basic matrix-based code adopted from modified FFIT mathematical formulas

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Table 5 Distribution of data (%) into body shapes and height groups using the FFIT technique Body shapes

Short

Average

Tall

Total

Rectangle

17

46.3

12.25

75.5

Bottom hourglass

0

0.5

0.25

0.8

Diamond

0.25

0.8

0.25

1.3

Inverted triangle

0

0.3

0

0.3

Oval

0.25

1.3

0

1.5

Spoon

0.25

1.0

1

2.3

Triangle

2.25

11.8

4.5

18.5

Hourglass

0

0.0

0

0.0

Top hourglass

0

0.0

0

0.0

Total

20

61.8

18.25

100

Table 5 shows the distribution of data (%) into body shapes and height groups using modified FFIT mathematical formulas. Maximum data falls under rectangle (75.5%) and triangle (18.5%) shapes among all height groups. The other shapes have less than 2% of the total data. Here, six size charts in rectangle and triangle shapes were prepared. This method managed to accommodate 94% of subjects from the sample population.

4 Discussion A comparative analysis of the three approaches showed interesting results in Table 6. The drop value-based approach led to maximum size groups (58) within 12 size charts, then FFIT with six size charts and a minimum of 30 size groups, and lastly ratio approach with four size charts having 21 size groups. Hsu developed a sizing system for Taiwanese women using a data mining approach and claimed it to be better than many other countries on the basis of minimum sizing groups present in it [43, 44]. As the number of sizing charts increases, the fit will be improved, but in a practical sense for manufacturers, it isn’t easy to accommodate too many size charts [24]. A number of size charts neither be too large nor be small; it must be moderate in number [8]. Therefore, in terms of the number of size groups, FFIT-based approach is the best among all, with 30 size groups and six sizing systems. On the other hand, the ratio method showed the highest coverage of 97.3% of the population among the three approaches; the drop value-based approach stands second with 96% of coverage, and the FFIT technique with 94%. Therefore, in terms of coverage % ratio, the approach was found to be the best. Aggregate loss of fit means determining the fit of clothing by measuring the distance between actual and assigned sizes (proposed sizes) [24].√The ideal value of aggregate loss considering two dimensions should be less than 2 = 3.6 cm. It was observed that in all three

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Table 6 Three selected approaches size chart’s shape categories, size groups, coverage percentages, and aggregate losses Body shape identification approach

Height category

Body shapes

Drop value

Short

Medium bust

6

Full bust

5

Large bust Average

Tall

No. of size charts

Coverage %

Aggreg. loss

12

6.8

2.02

7.0

2.68

4

4.0

2.34

Very small bust

5

3.0

2.52

Small bust

5

8.3

2.59

Medium bust

5

20.3

1.54

Full bust

6

18.8

1.51

Large bust

6

11.0

2.05

Small bust

5

3.5

2.83

Medium bust

4

4.5

2.48

Full bust

4

5.5

2.75

Large bust

3

3.5

1.58

58

96.0

2.24

Total Ratio

Short

Small bust

6

19.25

2.15

Average

Small bust

6

58.25

1.77

Medium bust

3

3.5

2.77

6

16.25

2.71

21

97.3

2.35

17

2.15

Tall

Small bust

Total FFIT

Size group

Short Average Tall Total

4

Rectangle

6

6

Triangle

3

2.25

2.45

Rectangle

6

46.3

1.52

Triangle

5

11.75

2.39

Rectangle

5

12.25

2.14

Triangle

5

4.5

2.37

30

94

2.17

cases using bust girth and height as the control dimension, the value of the aggregate loss was well below the cutoff value. The average aggregate loss value was found to be maximum in the ratio method (2.35), then the drop value approach (2.24) and the FFIT-based method had its minimum (2.17) value. Minimum aggregate loss means the distance between actual and assigned sizes is low; therefore, the garment is expected to have a better fit [24]. In aggregate loss terms, again FFIT approach was found to be best compared to others. Hence, FFIT software-based classification of shapes was chosen to develop a sizing system for plus-size women with a moderate number of size charts and the least aggregate loss value with moderate

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sample coverage. Additionally, the FFIT-based sizing system (without height categories) was already tested and applied by Staton (2019) for developing a sizing chart for US plus-size women, and the mathematical formulas of FFIT used for the current study were modified explicitly for plus-size bodies.

5 Conclusion Plus-size women’s bodies do not grow proportionally; therefore, conventional hourglass shape-based traditional pattern drafting methods will not work in this special category. Many past researchers emphasized considering body shapes while preparing sizing systems specifically for plus sizes. In order to find the most appropriate approach to data classification into body shapes, three body shape identification methods: drop value, ratio, and modified FFIT software’s mathematical formulas with three height groups (short, average, and tall) were applied on 400 plus size women’s key measurements. Most of the subjects fell under rectangle and triangle shapes when FFIT mathematical formulas were used; in the case of drop value majority came under medium to full bust shapes and the ratio method broadly divided data into small bust and medium bust shapes into all height categories. Once shapes were identified, three sizing systems were compared in terms of the cover percentage of the sample, the aggregate loss of fit, the number of size groups, and size charts. FFIT-based sizing system was found to be most appropriate for plus size women with 30 size groups under six size charts with an aggregate loss value of 2.17. After analyzing past studies on plus-size, FFIT-based classification of body shapes was found to be the most appropriate approach in the case of plus-sizes. Software base shape identification (FFIT) is robust, easy to execute, and can be applied to any data type.

References 1. Romeo L (2013) Exploration of plus-size female teens’ apparel fit and sizing in the United States 2. Rasband J, Liechty EG (2006) Fabulous fit: speed fitting and alteration. Fairchild Publications, New York 3. Simmons K, Istook CL, Devarajan P (2004) Female Figure Identification Technique (FFIT) for apparel part I: describing female shapes. J Text Apparel, Technol Manag 4 4. Rao N (2017) Fashion for plus-size people turned into big business now—The Financial Express. The Indian Express. https://www.financialexpress.com/lifestyle/fashion-for-plussize-people-turned-into-big-business-now/755388/. Accessed 1 May 2020 5. Morlock S, Schenk A, Klepser A, Loercher C (2020) Sizing and fit for plus-size men and women wear. In: Zakaria N, Gupta D (eds) Anthropometry, apparel sizing and design, 2nd edn. Elsevier Ltd. https://doi.org/10.1016/B978-0-08-102604-5.00014-7 6. Sokolowski SL, Bettencourt C (2020) Modification of the Female Figure Identification Technique (FFIT) formulas to include plus size bodies. In: Proc 3D bodytech 2020, pp 17–18

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7. Staton S (2019) Analysis of body shapes & fit in plus-size women using SizeUSA data. North Carolina State University. https://repository.lib.ncsu.edu/bitstream/handle/1840.20/36417/etd. pdf?sequence=1&isAllowed=y. Accessed 30 Apr 2020 8. Zakaria N, Ruznan WS (2020) Developing apparel sizing system using anthropometric data: body size and shape analysis, key dimensions, and data segmentation. In: Anthropometry, apparel sizing and design, 2nd edn. Woodhead Publishing, pp 91–121 9. Lee Y (2013) Anthropometric data analysis for body shape modeling in Korean. Korean J Phys Anthropol 26:61 10. Ashdown SP (1998) An investigation of the structure of sizing systems. A comparison of three multidimensional optimized sizing systems generated from anthropometric data with the ASTM standard D5585-94. Int J Cloth Sci Technol 10:324–341 11. Lee YS (2014) Developing apparel sizing systems for particular groups. In: Gupta D, Zakaria N (eds) Anthropometry, apparel sizing and design. Woodhead Publishing Limited, pp 197–254. https://doi.org/10.1533/9780857096890.2.197 12. Plutt JA (2011) Body cathexis, fit satisfaction, and fit preferences among black and white plus-sized women. The University of Akron 13. ASTM (2022) ASTM D6960-04—standard table of body measurements relating to women’s plus size figure type, sizes 14W-32W. ASTM Int. https://webstore.ansi.org/standards/astm/ast md696004. Accessed 31 Dec 2022 14. Alexander M, Pisut GR, Ivanescu A (2012) Investigating women’s plus-size body measurements and hip shape variation based on SizeUSA data. Int J Fash Des Technol Educ 5:3–12 15. Chowdhary U, Beale NV (1988) Plus-size women’s clothing interest, satisfactions and dissatisfactions with ready-to-wear apparel. Percept Mot Skills 66:783–788 16. Kind KO, Hathcote JM (2000) Speciality-size college females: satisfaction with retail outlets and apparel fit. J Fash Mark Manag 4:315–324 17. Kumari A, Anand N (2020) Development of size chart of key measurement for plus size women category in India | SciTechnol. J Fash Technol Text Eng 8:1– 8. https://www.scitechnol.com/peer-review/development-of-size-chart-of-key-measurementfor-plus-size-women-category-in-india-vqpU.php?article_id=12776. Accessed 8 Nov 2021 18. Zakaria N (2010) The development of body sizing system for school-aged children using the anthropometric data. Universiti Teknologi Mara 19. Chun J (2014) International apparel sizing systems and standardization of apparel sizes. In: Anthropometry, apparel sizing and design. Elsevier Ltd., pp 274–304 20. Hsu CH, Lin HF, Wang MJ (2007) Developing female size charts for facilitating garment production by using data mining. J Chin Inst Ind Eng 24:245–251 21. Xia S, Istook C (2017) A method to create body sizing systems. Cloth Text Res J 35(4):235–248 22. Zakaria N (2014) Infants and children: understanding sizing, body shapes and apparel requirements for infants and children. In: Designing apparel for consumers. Elsevier, pp 95–131 23. Zakaria N (2014) Body shape analysis and identification of key dimensions for apparel sizing systems. In: Anthropometry, apparel sizing and design. Woodhead Publishing, pp 95–119 24. Zakaria N, Gupta D (eds) (2019) Anthropometry, apparel sizing and design. Woodhead Publishing 25. Beazley A (1997) Size and fit: procedures in undertaking a survey of body measurements. J Fash Mark Manag 26. Vithanage C (2015) A novel approach in formulating a size chart for female pants. University of Moratuwa, Shri Lanka. http://dl.lib.uom.lk/handle/123/13706. Accessed 4 Jan 2023 27. Kwon O, Jung K, You H, Kim HE (2009) Determination of key dimensions for a glove sizing system by analyzing the relationships between hand dimensions. Appl Ergon 40(4):762–766 28. Petrova A (2007) Creating sizing systems. In: Sizing in clothing. Woodhead Publishing series in textiles. Elsevier Ltd., pp 57–87 29. Chung MJ, Lin HF, Wang MJJ (2007) The development of sizing systems for Taiwanese elementary-and high-school students. Int J Ind Ergon 37(8):707–716

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30. Hsu CH (2008) Applying a bust-to-waist girth ratio approach to develop body measurement charts for improving female clothing manufacture. J Chin Inst Ind Eng 25:215–222 31. Gupta D, Gangadhar BR (2004) A statistical model for developing body size charts for garments. Int J Cloth Sci Technol 32. Song HK, Ashdown SP (2013) Female apparel consumers’ understanding of body size and shape: relationship among body measurements, fit satisfaction, and body cathexis. Cloth Text Res J 31(3):143–156 33. Shin E, Saeidi E (2021) Body shapes and apparel fit for overweight and obese women in the US: the implications of current sizing system. J Fash Mark Manag 34. Kim Y, Song HK, Ashdown SP (2016) Women’s petite and regular body measurements compared to current retail sizing conventions. Int J Cloth Sci Technol. 28:47–64 35. Song HK, Ashdown SP (2011) Categorization of lower body shapes for adult females based on multiple view analysis. Text Res J 81(9):914–931 36. Song HK, Baytar F, Ashdown SP, Kim S (2022) 3D anthropometric analysis of women’s aging bodies: upper body shape and posture changes. Fash Pract 14(1):26–48 37. Simmons K, Istook CL, Devarajan P (2004) Female Figure Identification Technique (FFIT) for apparel part II: development of shape sorting software. J Text Apparel, Technol Manag 4. https://www.researchgate.net/publication/238103641_Female_Figure_Identification_Techni que_FFIT_for_apparel_part_II_Development_of_shape_sorting_software. Accessed 4 Dec 2020 38. Yim Lee J, Istook CL, Ja Nam Y, Mi Park S (2007) Comparison of body shape between USA and Korean women. Int J Cloth Sci Technol 19(5):374–391 39. Connell LJ, Ulrich PV, Brannon EL, Alexander M, Presley AB (2006) Body shape assessment scale: instrument development for analyzing female figures. Cloth Text Res J 24:80–95 40. Hamad M, Thomassey S, Bruniaux P (2017) A new sizing system based on 3D shape descriptor for morphology clustering. Comput Ind Eng 113:683–692 41. Uakarn C (2021) Sample size estimation using Yamane and Cochran and Krejcie and Morgan and Green formulas and Cohen statistical power analysis by G*power and comparisons. Apheit Int J 10:76–88 42. Rao BG (2016) Of size and suitability!. Apparel, pp 139–142. http://www.bindugopalrao.com/ wp-content/uploads/2016/09/Plus-size.pdf. Accessed 30 Apr 2020 43. Hsu CH (2009) Data mining to improve industrial standards and enhance production and marketing: an empirical study in apparel industry. Expert Syst Appl 36:4185–4191 44. Hsu CH (2009) Developing accurate industrial standards to facilitate production in apparel manufacturing based on anthropometric data. Hum Factors Ergon Manuf 19:199–211

Investigation of the Pressure Transmission Characteristics of Miniaturised Air Bladders for Medical Compression Textiles D. P. Hedigalla, M. Ehelagasthenna, G. K. Nandasiri, I. D. Nissanka, and Y. W. R. Amarasinghe

Abstract Compression therapy is considered as the cornerstone of treatment for all types of Chronic Venous Disease (CVD), which is the most prevalent vascular disease affecting the lower extremities. However, most of the existing medical compression textiles inherit a limitation of applying uniform pressure around the lower limb circumference. Previous research has shown that this limitation could be overcome by applying a radial force due to a pressure exerted by an air volume trapped inside a miniature bladder. Thus, this study analysed the pressure transmission characteristics of the miniature bladders via numerical modelling and laboratory experiments. The pressure transmission characteristics of miniaturised air bladders and the percentage of the area, where uniform pressure is applied were investigated for a variety of size and thickness parameters using numerical simulations. It was observed that the percentage of pressure transmission increased as the bladder size decreased while it increased as the thickness increased. Moreover, the percentage of area where the pressure is applied has a positive correlation with the bladder size while a negative correlation existed with its thickness. The experimental findings of this study further revealed that around 55% of the applied pressure into the miniaturised bladder was transmitted on a hard surface. Both experimental results and numerical simulations displayed similar results where the average interface pressure of the simulations had more than 95% agreement with the experimental pressure values obtained. Keywords Chronic venous disease · Compression therapy · Finite element analysis · Active compression · Miniaturised bladders

D. P. Hedigalla (B) · G. K. Nandasiri Faculty of Engineering, Department of Textile and Apparel Engineering, University of Moratuwa, Katubedda, Sri Lanka e-mail: [email protected] M. Ehelagasthenna · I. D. Nissanka · Y. W. R. Amarasinghe Faculty of Engineering, Department of Mechanical Engineering, University of Moratuwa, Katubedda, Sri Lanka © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024 D. Gupta et al. (eds.), Functional Textiles and Clothing 2023, Springer Proceedings in Materials 42, https://doi.org/10.1007/978-981-99-9983-5_8

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1 Introduction Chronic Venous Disease (CVD), the most common chronic disease influencing the lower limb [1–5], is considered as any functional or morphological irregularities of the venous system [1–5]. Its clinical signs vary from minor: telangiectasias and reticular veins, to severe: venous ulcers [1, 3, 6, 7] out of which varicose veins is considered the most widespread symptom of CVD [6]. Several risk factors like age, female sex, obesity, prolonged standing, and pregnancy are established for the initiation and progression of CVD as each of them may have an impact on many pathophysiological pathways [1–3, 8, 9]. The general populations of northern and western Europe frequently experience chronic venous disease than in Asians or Africans [6, 9]. The estimated prevalence of varicose veins ranges from 1 to 60% for women and 2–56% for men [6]. The significant difference in the estimated prevalence reflects disparities in the research population’s diversity, which includes differences in age, race, and gender as well as measuring techniques and disease diagnosis [6, 8]. In the United States, treatment cost for venous ulcers is estimated at $3 billion with a loss of 2 million working days [9] while in the UK estimated annual cost for managing patients with venous leg ulcers is over £2 billion [10]. Thus, by 2021 the global treatment market for varicose veins was USD 1.2 billion and it is expected to grow from 2022 to 2030 at a compound annual growth rate (CAGR) of 6.21% [11]. Even though a wide range of treatment methods exists for the CVD, compression therapy is considered as the mainstay treatment for all types of CVD affecting the lower extremities [1–3]. Compression therapy aims to counteract the hydrostatic forces caused by venous hypertension [12]. Thus, major veins are compressed sufficiently, resulting in a diameter reduction and speeding up the blood flow [3, 12]. Medical compression stockings (MCSs), medical compression bandages (MCBs), and intermittent pneumatic compression (IPCs) are just a few examples of the various compression devices that fall under the categories of passive or active compression [1–3, 12]. The pressure applied to the lower limb in passive compression treatments like MCBs and MCSs is inversely proportional to the limb’s radius (R) and directly proportional to the tangential tension component (T) developed in elastic materials due to its stretch [1–3, 13, 14]. Even though passive compression devices can apply a pressure gradient from ankle to knee level due to the elasticity of the textiles and the changing radius of curvature of the leg, they are incapable of applying a consistent compressive force around the leg circumference [1–3]. Furthermore, passive compression devices lose their elasticity over time as the nature of the material, stitching patterns, and the fabrication process influence the compression provided as well as the mechanical characteristics like stiffness, elasticity, and hysteresis [1–4]. Intermittent pneumatic compression devices with single bladder cuffs, multichamber cuffs are made up of inelastic chambers in the form of sleeves or boots and pneumatic pump equipped with gauges to exert intermittent compression at predetermined pressure levels [1–3, 15]. Even though single bladder cuffs can be inflated to uniform pressure, they fail to establish a pressure gradient from ankle to knee level as they extend and collapse entirely [1–3, 15]. Multi-chamber cuffs,

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which typically contain three to four compartments, can inflate their compartments one by one from ankle to knee with predetermined pressure levels, allowing for the required pressure gradient [15]. However, due to the larger size of the bladders, both intermittent pneumatic cuffs are bulkier and make it difficult to wear as well as expensive compared to MCSs and MCBs [1–3]. Thus, to address the existing shortcomings of the MCBs, MCSs, and IPCs, active compression devices based on active materials like shape memory alloys (SMAs), shape memory polymers (SMPs) and dielectric elastomer actuators (DEAs) have recently been explored [1–3]. However, these treatment approaches exert pressure on the lower limb in response to the tension developed due to its active material’s deformation and the radius of curvature of the limb. Thus, applying a uniform pressure around the circumference of the limb would not be possible [3]. In the recent past, an active compression sleeve with miniaturised air bladders in a hexagonal shape was developed such that it could exert a radial force by a volume of air trapped within the bladder, resulting in a uniform pressure applied on the lower limb was the inherent limitation of existing modalities like MCSs, MCBs and IPCs [1, 3]. Moreover, a numerical analysis of how a compression sleeve with miniature air bladders propagated pressure on skin, fat, and muscle layers also revealed that miniature air bladders might be able to exert uniform pressure in both longitudinal and transverse directions [3]. However, the pressure transmission characteristics of the compression sleeve designed with miniaturised air bladders for various parameters were not investigated in prior research. Thus, this study aims to investigate the pressure transmission characteristics along with the sensitivity of the percentage of the area where the uniform pressure is applied to the various parameters like side length and thickness of the proposed bladder unit via numerical modelling and laboratory experiments. The findings of this study could be used to determine the optimum mini-bladder sizes and arrangements for the creation of an active compression sleeve for the treatment of CVD.

2 Methodology 2.1 Design and Development of Miniaturised Air Bladders According to the literature the active compression sleeve designed with the miniaturised air bladders could overcome the existing limitations of compression modalities utilized for chronic venous disease [1, 3], where miniaturised air bladders were designed with one surface of the miniaturised air bladders in contact with the skin could be inflated, while inflation of all other surfaces was restricted to increase the pressure transmission efficacy. Thus, in the current study, two miniaturised bladder arrays were manufactured, each consisting of three hexagonal-shaped mini-bladder units. The mini bladders were designed with three layers: top layer, fabric layer, and bottom layer. The top layer is the layer that makes direct contact with the skin,

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Fig. 1 Manufactured miniaturised air bladders having a high-modulus PA-based textile layer bonded with carbon fabric as the fabric layer. a Top view b bottom view

whereas the bottom layer becomes the outermost layer when the miniaturized air bladder array is wrapped around the lower limb. Furthermore, a fabric layer sandwiched between the top and bottom layers was implemented to control inflation towards the outer side, ensuring that only the top layer can inflate and apply pressure while still maintaining flexibility. The top and bottom layers were crafted with Platsil® Gel OO30 (MouldLife, Suffolk, UK), a type of RTV silicone as it has low modulus and low shore hardness. Two types of mini-bladder arrays were manufactured where the key difference between the manufactured miniaturised air bladder arrays was the fabric layer, which consisted of one a polyamide (PA)-based textile layer (225.8 GSM) and another having this high modulus PA fabric bonded with a carbon fabric (443.8 GSM). Two types of mini-bladder arrays were manufactured with custom-made moulds and miniaturised air bladder array having a high-modulus PA-based textile layer bonded with carbon fabric as the fabric layer is depicted in Fig. 1.

2.2 Experimental Setup The test rig depicted in Fig. 2 was designed with a perspex cylinder of diameter 60 mm and three AMI air pack sensors to validate the simulation results with the experimental findings. The three AMI air pack sensors were placed onto the cylinder using a tape and the developed mini-bladder array was wrapped around the cylinder such that each AMI air pack sensor coincided with each mini-bladder. The minibladder unit was inflated to a different pressure level using a hand pump with a nonreturn valve which was connected to a Y connector, where one end was connected to the mini-bladder array and the other end to a back pressure sensor which was used to measure the inflated pressure. 1 ml of air was supplied at a time to inflate the mini-bladder unit to a range of pressures and the corresponding AMI air pack sensor readings and the back pressure sensor readings were recorded manually. This procedure was repeated five times for each bladder and plotted the average interface pressure values against the inflated pressure values for each bladder.

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Fig. 2 Experimental setup. (A) Transparent acrylic tube (B) AMI air pack sensor placed onto the acrylic tube (C) Mini-bladder array with high-modulus PA fabric bonded with carbon fabric in the textile layer (D) Main unit of AMI sensors (E) Y connector (F) Hand pump with non-return valve (G) Pressure sensor

2.3 Geometrical Model As this numerical study is to investigate the pressure transmission characteristics of the miniaturised air bladders, validation of simulation results with the experimental results was a primary requirement. Thus, a geometrical model of the mini-bladder unit consisted of three chambers and each chamber was built with three layers and the transparent acrylic hollow cylinder of a diameter of 60 mm was developed such that it represents the exact experimental setting. The three layers of the mini-bladder unit as depicted in Fig. 3 are: • Top elastomer layer: a 6 mm thickness elastomeric layer consisting of three air chambers of 2.5 mm height to denote the top-most layer of the mini-bladder unit.

Fig. 3 SolidWorks® design of the experimental setup. a Front view b Back view c Top Bottom view. (A) Transparent acrylic tube of 60 mm diameter (B) Top layer (inflatable layer) (C) Fabric layer (D) Bottom layer (non-inflatable layer)

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• Bottom elastomer layer: a 0.3 mm thickness elastomeric layer to represent the bottom-most layer of the mini-bladder unit. • Fabric layer: a 1.2 mm thickness layer sandwiched between the top and the bottom elastomer layers. To represent the transparent acrylic hollow cylinder where the mini-bladder array was wrapped, a hollow cylinder of 60 mm diameter and 100 mm height was designed. The entire model was developed in SolidWorks such that a 1 mm gap was allowed between the mini-bladder unit and the hollow cylinder. Thereafter, the entire model illustrated in Fig. 3 was converted into STEP format and simulated with ANSYS.

2.4 Material Models and Meshing To define the fabric layer and the top and bottom layers of the miniaturised air bladders in the ANSYS workbench, the Young’s modulus of the PA warp knitted fabric bonded with the carbon fabric and the material parameters of the hyperelastic model which perfectly represent the stress–strain behaviour of the used Platsil® GelOO30 (MouldLife, Suffolk, UK) were determined using experimental studies, and these experimentally determined values were used in the simulations. The young’s modulus of the fabric was evaluated using the ASTM D 5035 standard with the type 1R specimens and 300 mm/min test speed for the elongation at break. Five number of samples were tested for both warp and weft directions, the stress and strain curves were plotted from the obtained findings, and the Young’s modulus was calculated using the straight line of the linear part of the stress–strain curve. The strain–stress characteristics of the Platsil® Gel OO30 (MouldLife, Suffolk, UK) utilized in this research were determined according to the standard BS 37:2011 with the type 1A specimens and 500 mm/min test speed. Those results were analysed with the Yeoh first-, second-, and third-order models [1]. Material parameters of the Yeoh models were determined by curve fitting the engineering strain–stress relationships derived for different Yeoh models with the uniaxial experimental data [1]. Each layer of the mini-bladder unit and the hollow cylinder were specified on the ANSYS workbench based on the experimentally deduced material parameter as follows. • Top and bottom layers made with Platsil® Gel OO30 (MouldLife, Suffolk, UK) were characterised as a hyperelastic material and defined using Yeoh third order model with the material parameters C 10 = 2.58 × 10–2 MPa, C 20 = 1.464 × 10−3 MPa, and C 30 = −9 × 10−6 MPa and a density of 1100 kgm−3 . • The fabric layer made by bonding the carbon fabric and a PA warp knitted fabric was characterized as a linear elastic material and defined using Young’s modulus of 16.9315 MPa, density of 368.13 kgm−3 , and a Poisson’s ratio of 0.3. • The hollow cylinder was characterised as a linear elastic material with Young’s modulus of 2800 MPa, Poisson’s ratio of 0.4, and a density of 1190 kgm−3 .

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Then, all the geometries including the three layers of the mini-bladder unit and the hollow cylinder were meshed with first-order tetrahedron solid elements. A mesh sensitivity analysis was performed to identify a suitable mesh element size for all the geometries and 1.0 mm of mesh element size was chosen for the simulation.

2.5 Boundary and Loading Conditions The boundary conditions and the connections between each layer of the mini-bladder unit and between the top layer and the hollow cylinder were defined to replicate the experimental setup discussed in Sect. 2.2 and elaborated as follows: • Bonded contact between the top layer and fabric layer, and bonded contact between the fabric layer and bottom layer • Frictional contact between the surface of the top layer and the exterior surface of the hollow cylinder (coefficient of friction 0.5). • The bottom layer including the carbon fabric bonded with the PA-based warp knitted fabric, was designed, and developed to limit the inflation on the outer side, allowing to enhance the pressure transmission efficacy of the mini-bladder unit. Thus, the bottommost surface depicted in the Fig. 3 was set as fixed. • The inner surface of the hollow cylinder was also set as fixed. All the interior surfaces of the air chambers including the air channels were defined as the surfaces where the range of pressure is applied. A curved surface was defined on the exterior surface of the hollow cylinder to do the evaluation of the pressure transmission percentage and the area percentage where the uniform pressure is applied.

2.6 Data Analysis To validate the simulation setup with the experimental results, simulations were carried out for a range of pressures applied during the experiments. The von Mises stresses on the curved surface defined on the hollow cylinder were executed and the results were used in the further analysis using Python software. As it was required to ignore the von Mises stresses on the places where the mini-bladder does not touch the cylinder in calculating the average interface pressure, the von Mises stresses of each facet were characterised based on the observed pressure values. The average interface pressure exerted by the mini-bladders on the cylinder surface was computed by dividing the sum of the von Mises stresses of the facets where the mini-bladder unit was contacted by the total number of facets at those points. A graph of the average interface pressure against the inflated pressure was plotted and compared with the experimental results obtained. The validated simulation model was then used to model the interface pressures at different input pressures from 4 to 13 kPa

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with geometric parameters of 4 sizes: 1, 1.5, 2.0, 2.5 cm, and 3 thicknesses of: 1.5, 2.0, 2.5 mm of the mini-bladder unit to establish the optimum design parameters for the mini-bladder unit.

3 Results and Discussions 3.1 Pressure Transmission Characteristics of the Manufactured Mini-bladder Arrays The interface pressure between mini-bladder arrays and the acrylic tube against the inflation pressure for the mini-bladders are depicted in Fig. 4a, b, respectively. The three curves depicted in Fig. 4a, b belong to the pressure transmission percentage of three hexagonal-shaped mini-bladders in a unit. Figure 4 a depicts that the percentage of pressure transmission increased up to 25 mmHg inflation pressure, then started to gradually decrease. This could be attributed to the inflation of the bottom layer of the mini-bladder due to higher inflation pressures than 25 mmHg rather than the surface that is in contact with the acrylic tube. However, Fig. 4b depicted that the minibladder array manufactured with PA fabric bonded with carbon fabric, illustrated the pressure transmission percentage increased initially and reached a plateau of 50– 60% of the inflation pressure. Thus, it was decided to use the PA fabric bonded with carbon fabric as a layer to successfully restrict the bottom layer inflation, and was used in the final design of the mini-bladders to validate the simulation results.

Fig. 4 Pressure transmission characteristics of the mini-bladder a made with only PA warp knitted fabric as the textile layer b made with PA based warp knitted fabric bonded with carbon fabric as the textile layer

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Table 1 Young’s modulus of PA fabric bonded with carbon fabrics cut along the warp and weft direction Sample number

Young’s modulus (MPa)

Sample number

Young’s modulus (MPa)

Along the warp direction

Along the weft direction

Sample 01

17.634

Sample 01

18.097

Sample 02

17.612

Sample 02

17.341

Sample 03

15.926

Sample 03

16.269

Sample 04

16.038

Sample 04

16.026

Sample 05

16.570

Sample 05

17.804

Average

16.756

Average

17.107

3.2 Determination of the Young’s Modulus of PA Fabric Bonded with Carbon Fabric Young’s modulus of all five samples for warp and weft were tabulated in Table 1. As the stress was not applied solely in one direction of the fabric, Young’s modulus of 16.9315 MPa, which was calculated by averaging the Young’s modulus in warp and weft direction, was used in the subsequent stages of modelling the inflation behaviour of the mini-bladder array.

3.3 Determination of the Material Parameters of Yeoh Hyperelastic Models The curve fitting plots of Yeoh’s first-, second-, and third-order models for uniaxial test data of Platsil® GelOO30 are shown in the Fig. 5. The average material parameters and statistical measures of each model for uniaxial test results were tabulated in Table 2. The curve fitting plot of Yeoh first-order model depicted in Fig. 5 a displays a higher deviation from all the uniaxial test data for Platsil® Gel OO30 (MouldLife, Suffolk, UK). Moreover, the statistical measures summarised in the Table 2 reveal that the Yeoh first-order model does not completely represent the uniaxial test data of Platsil® Gel OO30 (MouldLife, Suffolk, UK). In comparison to the curve fitting plots of Yeoh first-order model, the Yeoh second-order model could be used to describe the behaviour of Platsil® Gel OO30 (MouldLife, Suffolk, UK) as the average R2 value is 0.988 which is more than the value of first-order model as well as it has a lower RMSE and SSE. However, the Yeoh third-order model was the best fit for the uniaxial test data of Platsil® Gel OO30 (MouldLife, Suffolk, UK) as the average R2 value is 0.999 which was the highest among the other two models like Yeoh first- and second-order models. Moreover, the average RMSE and SSE are 0.008 and 0.008, respectively, which are the lowest compared to that of curve fitting data of Yeoh first- and second-order models. Thus, Yeoh third-order model was used in predicting the behaviour of Platsil® Gel OO30 (MouldLife, Suffolk, UK) material with C 10 = 0.0258 MPa, C 20 = 0.0015 MPa, and C 30 = −0.000009 MPa material parameters.

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Fig. 5 Uniaxial test data of Platsil® GelOO30 (MouldLife, Suffolk, UK) with curve fitting plots of a Yeoh first-order model b Yeoh second-order model c Yeoh third-order model

Table 2 Average material parameters and statistical measures of Yeoh first-, second-, and thirdorder models for Platsil® Gel OO30 (MouldLife, Suffolk, UK) Model name Material constants

Statistical data

C10 (MPa)

C20 (MPa)

C20 (MPa)

RMSE

SSE

R2

Yeoh 1st order

0.0850

–

–

0.1753

4.7193

0.8765

Yeoh 2nd order

0.0421

0.0007

–

0.0552

0.4787

0.9879

Yeoh 3rd order

0.0258

0.0015

0.0001

0.0088

0.0079

0.9997

3.4 Numerical Results of the Miniaturised Air Bladders The interface pressure distribution on the outer surface of the Perspex tube is shown in Fig. 6a while the deformation profile of the mini-bladder array is depicted in Fig. 6b for the hexagonal-shaped miniature air bladders at 2.5 cm in length, 2.0 mm in thickness, and 7000 Pa inflated pressure. The green-coloured area is the region where the uniform pressure is applied which is further revealed that the miniaturized bladders could be able to apply a uniform pressure.

Fig. 6 Simulation results of the mini-bladder array with 2.5 cm side length, 2.0 mm thickness @7000 Pa a interface pressure b deformation profile

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3.5 Comparison of the Experimental Results with Numerical Results The plot of average experimental interface pressure against inflated pressure of the mini-bladder array was depicted in Fig. 7 for a range of 0–100 mmHg inflation pressure. The three plots depicted in Fig. 7 a belong to the interface pressure at three hexagonal-shaped mini-bladders in a unit. It could be observed that the pressure values nearly represent each other and only one curve slightly deviates from the other two at pressures greater than 30 mmHg. The plots of average simulated pressure and experimental interface pressure against the inflated pressure of the mini-bladder array were depicted in Fig. 7b–d. The average value of R2 obtained for the three plots illustrated in Fig. 7 is more than 95%, where the numerical model could be used to determine the interface pressure for bladders with a range of parameters like thickness, and size of mini-bladders.

Fig. 7 a Interface pressure between the transparent acrylic cylinder and the three hexagonal-shaped mini-bladders against inflated pressure b–d comparison of experimentally measured values with the numerical simulated values

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3.6 Pressure Transmission Characteristics at Various Side Lengths and Thickness The plots of pressure transmission characteristics at four different side lengths; 1.0, 1.5, 2.0, and 2.5 cm against inflated pressure ranging from 4 to 13 kPa (30– 97.5 mmHg) are shown in Fig. 8. Three curves at each of the plot represent the pressure transmission at three different thicknesses; 1.5, 2.0, and 2.5 mm. Thus, the significance of the percentage of pressure transmission at thicknesses, and side lengths against the inflated pressure is illustrated as minimal. However, the percentage of pressure transmission at different side lengths is increased as the thickness of the top layer (membrane) of the mini-bladder is increased. The highest percentage of pressure transmission was recorded around 65% from the mini-bladder array manufactured with 1.0 cm side length and 2.5 mm thickness, while the lowest percentage of pressure transmission of 53% was recorded from the mini-bladder array manufactured with 2.5 cm side length and 1.5 mm thickness. When the thickness of the top layer was increased from 1.5 to 2.5 mm with 0.5 mm increments, a 1–2% increase in the percentage of pressure transmission was observed with the change of the thicknesses for all the side lengths. However, the side length of the mini-bladders at any thickness level was increased from 1.0 to 2.5 cm by 0.5 cm increments, thus a 2–3% change of pressure transmission percentage was recorded. Hence, it can be concluded that the significance of the side length on the percentage of pressure transmission is greater than that of the thickness. Moreover, the

Fig. 8 Pressure transmission characteristics against inflated pressure at four different side lengths: a 1.0 cm b 1.5 cm c 2.0 cm d 2.5 cm

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percentage of pressure transmission is decreased as the side length of the mini-bladder is increased. When inflating miniaturised air bladders made from Platsil® GelOO30 (MouldLife, Suffolk, the UK), the material’s elasticity can cause a portion of the applied pressure to be absorbed within the bladder material itself rather than being fully transmitted. As a result, when the side length of the mini-bladder increases, the area where inflation occurs also increases. This leads to a greater amount of pressure being absorbed by the material, resulting in a decrease in pressure transmission.

3.7 Percentage of Area Where the Uniform Pressure Applied at Various Side Lengths and Thicknesses Most of the existing compression modalities except for the compression sleeve designed with miniaturised air bladders could not apply a uniform pressure around the limb circumference as the radius of curvature of the lower limb changes. Thus, it is important to consider the percentage of the area where the uniform pressure is applied when designing a compression device with miniaturised air bladders. Hence, the plots of the percentage of the area where the uniform pressure is applied at four different side lengths: 1.0, 1. 5, 2.0, and 2.5 cm and three different thicknesses:1.5, 2.0, and 2.5 mm against inflated pressure ranging from 4 to 13 kPa are depicted in Fig. 9. Three curves in each plot represent how the uniform area percentage changes as the thickness of the top layer of the mini-bladder changes from 1.5 to 2.5 mm. As could be observed from the plots, a positive correlation exists between the area where the uniform pressure is applied and the side length of the hexagonal-shaped mini-bladder while a negative correlation exists between the uniform area percentage and the thickness of the top layer. However, the significance of inflated pressure on the uniform area percentage is negligible at any side lengths and thicknesses. The highest percentage of the area where the uniform pressure is applied, was recorded as about 65% of the total area of the mini-bladder array manufactured with a 2.5 cm side length and 1.5 mm thickness. The lowest percentage of the uniform area was recorded as about 26% of the total area of the mini-bladders manufactured with 1.0 cm side length and 2.5 mm thickness. When the thickness of the top layer is increased from 1.5 to 2.5 mm with 0.5 mm increments while keeping the side length constant, a 3–5% increase in the percentage of area where the uniform pressure is applied is recorded. However, side length at any thickness changed from 1.0 to 2.5 cm by 0.5 cm increments, and the percentage of the area where the uniform pressure was applied, increased by 10%. Thus, it can be concluded that the side length has a greater impact on the uniform area % than the top layer thickness.

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Fig. 9 Uniform area percentage against inflated pressure at four different side lengths: a 1.0 cm b 1.5 cm c 2.0 cm d 2.5 cm

4 Conclusions Chronic venous disease is an extremely concerning medical condition that affects the human lower limb as well as creates a significant impact on the total healthcare budget of many countries. This study investigated the use of miniaturised air bladders to design an active compression textile that could exert uniform pressure around the lower limb by a radial force generated due to the volume of air bladders trapped inside the bladders. During this study, the sensitivity of pressure transmission percentage as well as the uniformity of the pressure profile generated by the miniaturized bladders to the size and the thickness was investigated using numerical simulations. Further, the experimental study was used to validate the simulation setup. The analysis of pressure transmission characteristics of miniaturised air bladders was extended to sizes of 1.0, 1.5, 2.0, 2.5 cm, and thicknesses of 1.5, 2.0, 2.5 mm. The results of the study revealed that the pressure transmission percentages had a positive correlation with the thickness of the miniaturised bladder while a negative correlation existed with the size of the miniaturised bladder. Moreover, the area where the uniform pressure is applied has a positive correlation with the size of the miniaturised bladder while a negative correlation existed with the thickness of the miniaturised bladders. Thus, an optimization study is required to establish optimum miniaturised bladder parameters for effective pressure transmission while maintaining a higher uniform pressure area resulting uniform pressure profile, which would be the future direction of this research.

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Acknowledgements The authors would like to thank the Senate Research Committee, University of Moratuwa for the grant SRC/LT/2020/10. The authors wish to acknowledge the Department of Textile and Apparel Engineering and the Department of Mechanical Engineering, University of Moratuwa, Sri Lanka, for providing facilities to conduct the research.

References 1. Nandasiri HM (2019) A study of use of mini-bladders in active compression as a treatment for venous disease and lymphoedema 2. Nandasiri GK, Ianakiev A, Dias T (2020) Hyperelastic properties of platinum cured silicones and its applications in active compression. Polymers 12:19–23 3. Hedigalla D, Ehelagasthenna M, Nissanka ID, Amarasinghe R, Nandasiri GK (2022) Numerical study to investigate the pressure propagation patterns by a compression sleeve with miniaturised air-bladders. Moratuwa engineering research conference (MERCon 2022). Moratuwa, Sri Lanka, pp 1–5 4. Liu R, Guo X, Lao TT, Little T (2016) A critical review on compression textiles for compression therapy: textile-based compression interventions for chronic venous insufficiency. Text Res J 87:1121–1141 5. Beebe-Dimmer JL, Pfeifer JR, Engle JS, Schottenfeld D (2005) The epidemiology of chronic venous insufficiency and varicose veins. Ann Epidemiol 15:175–184 6. Ortega MA, Fraile-Martínez O, García-Montero C, Álvarez-Mon MA, Chaowen C, RuizGrande F, Pekarek L, Monserrat J, Asúnsolo A, García-Honduvilla N, Álvarez-Mon M, Bujan J (2021) Understanding chronic venous disease: a critical overview of its pathophysiology and medical management. J Clin Med 10:3239 7. Cleanthis M, Lees T (2011) Varicose veins and chronic venous insufficiency. Postgrad Vasc Surg 204–219 8. Robertson L, Evans C, Fowkes FG (2008) Epidemiology of chronic venous disease. Phlebol: J Venous Dis 23:103–111 9. Wolinsky CD, Waldorf H (2009) Chronic venous disease. Med Clin North Am 93:1333–1346 10. Phillips CJ, Humphreys I, Thayer D, Elmessary M, Collins H, Roberts C, Naik G, Harding K (2020) Cost of managing patients with venous leg ulcers. Int Wound J 17:1074–1082 11. Varicose veins treatment devices market size report (2030) https://www.grandviewresearch. com/industry-analysis/varicose-veins-treatment-devices-market. Accessed 20 Jan 2023 12. Sarı B, O˘glakcıo˘glu N (2016) Analysis of the parameters affecting pressure characteristics of medical stockings. J Ind Text 47:1083–1096 13. Davies AH (2019) The seriousness of chronic venous disease: a review of real-world evidence. Adv Ther 36:5–12 14. Jawad AKJA (2010) Pressure mapping of medical compression bandages used for venous leg ulcer treatment 15. Berszakiewicz A, Siero´n A, Krasi´nski Z, Cholewka A, Stanek A (2020) Compression therapy in venous diseases: current forms of compression materials and techniques. Adv Dermatol Allergol 37:836–841

Eco-Friendly Dyeing and Finishing

Eco-Friendly Dyeing and Finishing for Improving Colour Fastness and Wellness Properties of Cotton Pubalina Samanta, Asis Mukhopadhyay, and Adwaita Konar

Abstract A comparative assessment of the performance of double sequential prebio-mordanting was carried out using tannin-rich harda, gall nut, and natural alum for dyeing cotton with catechu. The best performance was obtained by pre-mordanting with 15% gall nut + alum (25:75) applied in sequence, showing better colour yield and moderate colour fastness to wash, light and rubbing as compared to other combinations of dual pre-mordanting for dyeing the cotton with 30% catechu (equivalent to 3% shade depth). Enhancement of colour fastness to washing (1 grade higher) and rubbing (½ grade higher) was observed post-treatment with 2% chitosan or 0.2% nano-chitosan by pad-dry-cure method. Post-treatment on catechu-dyed cotton fabrics with (i) hot aqueous extract, (ii) ethanolic extract (using EtOH + Water − 50:50), and (iii) microwave irradiated extract of eucalyptus leaves with lemon juice as catalyst enhances light fastness to 4–5 or 6, antimicrobial rating to 99% reduction for bacteria and UV protection factor (UPF) up to 45–50 as best results, as compared to 2% ZnO/0.2% Nano-ZnO finish as a mineral-based UV absorber and hydroxybenzotriazole as commercial UV-absorber. This dual bio-pre-mordanting with alum + gall nut and bio-dyeing with catechu, and bio-finishing with ethanolic extract of eucalyptus is found useful for the production of antimicrobial and UV-resistant protective medical textiles as wellness properties of cotton. Keywords Bio-mordant · Catechu · Eucalyptus · Nano-chitosan · UV protection finish (UPF) · Antimicrobial finish

P. Samanta (B) Department of Fashion and Apparel Design, Rani Birla Girls’ College, 38 Shakespeare Sarani, Kolkata, West Bengal 700 017, India e-mail: [email protected] P. Samanta · A. Mukhopadhyay Department of Jute and Fibre Technology, IJT, University of Calcutta, 35, B C Road, Kolkata, West Bengal 700 019, India A. Konar Government College of Engineering and Textile Technology, 12, William Carey Rd, Serampore, Hooghly, West Bengal 712201, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024 D. Gupta et al. (eds.), Functional Textiles and Clothing 2023, Springer Proceedings in Materials 42, https://doi.org/10.1007/978-981-99-9983-5_9

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1 Introduction Cook [1] has made a brief review of the fastness properties of the variety of dyes and methods for improvement of colour fastness on different textile fibres and dyes combinations in different ways [2, 3]. Different factors affecting light and wash fastness for natural dyes are reported in a recent review by Samanta [4, 5]. Gupta [6] has mentioned the influence of the molecular structure of natural dyes on colour fastness rating. Application of natural plant based-dyes, natural-mordants, and natural-plant-based finishing on cotton and jute textiles has been reported recently by Samanta [7]. Colour fastness to washing depends also on the chemistry and functionality of the fibres, molecular structure, and chemistry of natural mordants and/mordanting assistants, type of dye structure, and type of post-treatment besides the type of wash liquor and conditions of washing and many other factors [8–10]. Cristea [3], Lee [11], and Micheal [12] have made various approaches to improve overall colour fastness for a few natural dyes. Samanta et al. [13–15] and Singhee et al. [16] have reported optimization of mordanting and dyeing conditions for achieving optimum colour strength and improved colour fastness to washing for jute and cotton fabrics, using different mordants and natural dyes. Sinnur and Samanta et al. [17] have studied the effects of dual mordanting agents, optimization of dyeing process conditions, and UV-resistant action of Punica (pomegranate rind) for its application on the cotton khadi fabric. There are scanty studies on gall nut as a bio-mordant and catechu as an antimicrobial natural dye and eucalyptus as a UV absorber as well as an antimicrobial finishing agent from natural sources. Hence, an attempt has been made in this present work for eco-friendly dyeing and finishing of cotton with gall nut + alum as dual bio-mordants, catechu as an antimicrobial natural dye, and eucalyptus leaves extract as UV absorber cum antimicrobial finish and chitosan as nature resource-based antimicrobial agent. Oak Gall nut contains 60–70% gallo-tannins, some amount of ellagic acid, gallic acid, polyschacaride, gluco-methy-gallate, etc. [18–20] and is therefore considered more suitable to be used for tannin-rich bio-mordant than harda due to the higher tannin content of gall nut as compared to myrobolan or harda [21]. The main tannin-rich colour components of catechu are catechin, quercetin, and flebo-tannins. Flebo-tannin contains catechu-tannic acid (22–30%), aca-catechin (10–12%), catechu red, epi-catechin, and some gummy matter, besides quercetin and catechin (2–12%) out of crude catechin content 12–33% [22] as a tannin-rich natural colourant. Catechin is not soluble in cold water. Hot aqueous extraction of catechu derives mainly pure catechin, flebo-tannins (catechu-tannic acid and saponin, etc.), and quercetin i.e., all the said three colour components, which are dissolved preferably in hot water after pre-soaking in alkali [22]. Chitosan (chemically a linear polysaccharide (β-1-4 linked residue of N-acetyl2-amino-2-deoxy-D-glucose) is soluble in aqueous acidic media, as the protonation of −NH2 group of chitosan is only possible in acid media and its pKa Value is

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approx.6.5, when at least 50% amino groups are protonated. It has different applications like antimicrobial criteria and is also used for the cationization of cotton textiles, and for subsequent dyeing with anionic dyes without salt [23]. Chemical compositions of the steam distillate of eucalyptus wood bark and leaves (E. globulus) were analysed by GC–MS [24] and major identified compounds from the eucalyptus leaves with essential oil are 1,8-cineole (eucalyptol approx. −51.62%) and other compounds like a moderate amount of α-pinene (23.62%), and lower amount of p-cymene (10%), β-myrcene (8.74%), Terpinen-4-ol (2.74%) and γ-terpinene (2.59%) as well as a minor amount of saponin amongst the major compounds found for Eucalyptus Globulus L variety of eucalyptus leaves extract, which is used in the present work as a natural finishing agent having both antimicrobial and antioxidative UV-protective criteria. Hence, the present work assumes the novelty of the use of dual bio–mordanting, bio-dyeing, and bio–finishing together applied in sequence on cotton to produce antimicrobial and UV-resistant natural dyed eco-friendly cotton textiles improving colour fastness and wellness properties of cotton as protective medical textiles.

2 Materials and Methods 2.1 Fabrics Desized, scoured, and bleached 100% cotton plain weave shirting fabric, 84 ends per inch, warp count of 9.8 tex and 74 picks per inch, weft count 10.7 tex, areal density of 145 g/m2 and thickness of 0.25 mm was procured was used for the study. It was de-sized, scoured, and bleached with H2 O2 before use.

2.2 Chemicals Commercial-grade acetic acid (CH3 COOH) and sodium acetate and sodium acetateacetic acid buffer for adjusting pH4-4.5 and 1% sodium hydroxide solution sodium chloride (NaCl) as electrolyte/as exhaustive agent NaCl salt, all obtained from EMerck (India) were used. The rest of the chemicals are obtained from local suppliers.

2.3 Mordants Natural alum (Potash alum, i.e., K.Al (SO4 )2, 12H2 O) and Natural Harda (Terminalia chebula), and Gall Nut (Quercus Infectoria,) collected from the local market were used in this work.

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2.4 Natural Dye Catechu Catechu (Acacia catechu) is obtained from the heartwood of the cutch tree, belonging to the Leguminosea family was used.

2.5 Finishing Agents Chitosan. Chitosan is the amino group-containing poly-cationic compound obtained naturally in shell-fish as chitin which on deacetylation forms chitosan. It is chemically a linear polysaccharide (β-1-4 linked residue of N-acetyl-2-amino-2-deoxy-Dglucose) as a linear bio-compatible amino-polymer having antibacterial/antifungal criteria [23]. Eucalyptus leaves (Eucalyptus globulus). The Eucalyptus leaves and barks have polyphenol-based tannins compounds (approx.11%) containing gallo-tannins, gallic acid, ellagic acid, and flavonoids like quercetin, rutin, and hyperoside as its pale yellow to light brown colour compounds. Its methanolic extraction includes eucalyptol (1–8 cinepole), eriodictyol, rhamnazin, and toxifolin having antioxidant and very good UV-absorbing nature [24–27].

2.6 Extraction of Gall Nut Gall nut was extracted in aqueous media from the grounded powder of gall nut following optimal extraction conditions at pH-11, MLR 1:20, extraction temperature 80 °C and extraction time of 45 min [28] and finally was strained in 60 mesh nylon fabric to get a light yellow solution of gallo-tannins to use as bio-mordant/mordanting assistant for dyeing of cotton with catechu with or without alum as natural metallic mordant as combined/dual mordant system.

2.7 Extraction and Purification of Catechu Catechu solution was prepared by dissolving pre-weighed dry chunks of catechu, after pre-soaking of catechu chunk in alkali for 1 h [29] to make it easily soluble. Alkali pre-soaked catechu chunk was heated under a water bath at around 50–60 °C for 60 min, at MLR 1:20, at pH 12, by addition of a small amount of 1% caustic soda [29], followed by straining it in 60 mesh nylon filter cloth. The filtrate was then neutralized with acetic acid at a pH of 6–7, to get the dye liquor of 30% catechu (on oven-dry mass of source materials) extract, which is equivalent to 3% purified dye solution.

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Purification of catechu (Acacia catechu) dye chunk was carried out by Soxhlet extraction and distillation using ethyl alcohol + benzene mixture (50:50) for 6 h for 10 cycles. After purification, it was observed that 30gm catechu dry chunk produced only 3 gm of purified catechu dye, indicating 3% pure catechu, i.e., actual shade depth will be 3%, when aqueous extract of 30% dry catechu source material was used for dyeing.

2.8 Solubilization of Chitosan and Nano-chitosan Normal chitosan powder (85–90% de-acetylated) was initially pre-soaked in 10% acetic acid solution overnight and was boiled at 90 ° C for 30 min in the 50:50 volumetric mixture of water and isopropyl alcohol in the presence of acetic acid. The boiled chitosan solution was cooled and strained in 60 mesh nylon filter fabric to obtain 2% chitosan solution. For preparing 0.2% nano-chitosan solution, 1.0 g of nano-chitosan powder was pre-soaked in 500 mL of 1% acetic acid. To prevent agglomeration, homogenization of nano-chitosan solution was carried out with dropwise addition of sodium salt of Tri-Phenyl Phosphate (STPP) and Nonidet p-40 (surfactant cum emulsifier), with a high-speed magnetic stirrer for 1 h. [30, 31] for breaking up agglomeration of nanochitosan to obtain the average size of nano-chitosan as 275 nm varying from 100 to 1000 nm [32, 33].

2.9 Extraction of Eucalyptus Leaves Extraction of eucalyptus leaves for its use as a strong natural resource-based UV absorber cum light fastness improver and antimicrobial finishing agent, three different ways of its extraction were carried out: Aqueous Extraction. 100 g of eucalyptus dried leaves (solid dry mass) was poured in distilled water of 1L at pH 5–5.5 (by adding 10% acetic acid solution dropwise) for extracting its major hot aqueous soluble components at 80 ° C for 30 min, from eucalyptus leaves, followed by cooling and filtering to obtain final eucalyptus aqueous solution. Aqua-Alcoholic Extraction. Similarly, 100 gm of eucalyptus dried leaves was poured into 1L of 50:50 (Water: EtOH (Ethanol) mixture for aqua-alcoholic extract) at the same pH of 5–5.5 followed by subsequent heating at 50 ° C for 30 min followed by cooling and filtering, to obtain the filter as light yellow aqua-alcoholic extract of eucalyptus leaves. Microwave Irradiated (Physical Intervened) Extraction. A dry mass of 100 gm eucalyptus leaves was taken in 1L of water maintaining the same pH at 5 to 5.5 and was subjected to microwave-irradiated heating at about 50 °C for 10–15 min

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using a microwave-safe Borosil glass beaker, followed by cooling and filtering to obtain microwave heated extract.

2.10 Preparation of Nano Zinc Oxide ZnO nano-particle was prepared by co-precipitation from zinc acetate dihydrate by adding 2 M NaOH solution drop by drop on Zn-acetate with stirring by a high-speed magnetic stirrer for 2 h. The watery gel precipitate of ZnO was collected as residue on filtering, followed by ethanol wash and drying in a vacuum oven for 6 h. This dried residue of ZnO white powder was then calcinated at 600 °C for 4 h in a muffle furnace to get d ZnO-nano-powder [34, 35].

2.11 Dyeing of Cotton with Catechu Gall nut 15% + alum (25:75) dual pre-mordanted cotton fabric was put into the 30% catechu extracted dye liquor bath and continued dyeing by heating the dye bath at a rate of about 2 °C per minute using RBE make lab beaker IR dyeing machine, to raise the final dyeing temperature up to 70 °C, continued for 60 min. with 5gpl NaCl salt added in two instalments at 15 min intervals in the first 30 min following optimum dyeing conditions as obtained earlier in our separate study communicated elsewhere, maintaining dye bath pH as 4.5–5, MLR-1:30, dyeing time—60 min and dyeing temperature max-at 70 °C and salt concentration −5 gpl. Finally, all dyed cotton samples were rinsed and washed thoroughly in running tap water and then soaped with 2 gpl soap at 50 °C for 15 min for removal of adhered and non-bonded dyes, followed by washing and final air-drying.

2.12 Post-dyeing––Finishing Treatments Finishing with Chitosan and Nano-chitosan. Selective catechu-dyed cotton fabrics were padded maintaining 100% wet pick up using 2% chitosan solution and homogenized 0.2% nano-chitosan solution both with further addition of 1% acetic acid and 1/5th part of citric acid by pad -dry (at 100 °C for 5 min) and cured (at 120 °C for 3 min). Lower temperature and time of curing were opted, as above this temperature and time of curing, chitosantreated cotton became yellower, particularly for −NH2 or NH-CH2 -R amino groups (containing chitosan) for improving wash fastness and rubbing fastness and antimicrobial property too. Finishing with ZnO and Nano-ZnO. Normal ZnO (2%) and nano-ZnO powder (0.02% and 0.2%), both before application, were admixed with 10 ml of hydroxymethyl-amino silicone (HMAS) polymer and water to make up 100 ml volume and

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stirred to make a homogeneous dispersion of both. Citric acid catalyst (1/5th of ZnO used) was then added in the said two dispersions. Selected samples of catechu-dyed cotton fabrics were then immersed into both types of ZnO dispersion using different trays and were batched for 30 min. After soaking and batching, the fabric samples were subjected to padding (at 100% weight pick up)–drying (at 100 °C for 5 min) and curing (at 120 °C for 3 min), keeping drying, curing temperature, and the same timeas used in chitosan finish for comparative purposes. Finishing with Extracts of Eucalyptus Leaves. Selective catechu-dyed cotton fabric samples were subjected to post-dyeing finishing with eucalyptus leaf extract using each of the three different types of 10% extract of eucalyptus leaves, i.e., aqueous extract, 50:50 Water + EtOH mixture extract and microwave irradiated aqueous extract, with further addition of 1/5th of acidic catalyst (5 gpl lemon juice or equivalent citric acid) subjecting to pad (at 100% weight pick up)—dry (at 100 °C for 5 min) and cure (at 120 °C for 3 min) process, keeping drying, curing temperature and time same as used in chitosan finish for comparative purposes.

3 Testing and Evaluation Methods 3.1 Reflectance, K/S Value, Colour Difference, and Related Other Colour Parameters Reflectance (R) and surface colour strength (K/S values) of control and selective dyed and/or finished cotton fabric samples were measured in a computer-aided reflectance spectro-photometer (Make: M/S Premier Colour Scan Pvt Instrument Ltd., Model SC 5100A) using Kubelka–Munk equation [36]. Total colour difference values (ΔE), changes in Chroma (ΔC*), changes in Hue (ΔH), and Metamerism Indices: (MI) were measured as per CIELAB colour space 1976 standard equations [36]. Brightness Index (BI) was measured as per the ISO2470-1977 method. Colour difference index (CDI) values represent the overall effects of all major colour difference parameters between sample 1 (standard) and sample 2 (produced), when dyed under different conditions, indicating dispersion of colour difference values indicating the overall effects of colour variations in a dyed sample. So, higher CDI values indicate a more critical dyeing parameter for colour variation. Colour difference Index (CDI) was calculated by Eq. 1. As an established empirical relationship obtained from earlier literature [37]: Colour Difference Index (CDI) = (ΔE × ΔH) / (ΔC × MI)

(1)

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3.2 Evaluation of Colour Fastness Properties Colour Fastness to Wash. Colour fastness to washing of the dyed cotton swatches (10 cm × 4 cm) was assessed as per ISO-II (IS: 3361-1979) method [38], by washing the sample with a standard soap solution (5 gpl) at 50 °C for 45 min, with MLR at 1:50 using Sasmira, Mumbai top loading washing fastness tester (Launder-O-Meter). Colour Fastness to Crocking/ Rubbing. Dry rub/crocking fastness of the dyed cotton swatches was assessed following the IS: M766-1988 method [38], using a motorized electronic-Mag-Solvic semi-automatic crock meter. Colour Fastness to UV Light. Colour fastness to sun-light/UV-light for dyed cotton swatches was assessed following IS: 2454-1985 method [38], using a Philips 500-W UV-light source in a Shirley-UK make MBTF-lamp micro-scale-fade-ometer along with 8 blue wool standard swatches (BS 1006: BOI: 1978) exposed simultaneously.

3.3 UV Protection Factor (UPF) Selective dyed and finished cotton fabrics swatches were tested to determine UV protection factor (UPF) by AATCC: 183:/2004 test method as amended in 2010/ 2014 (equivalent to AS/NZ 4399:1996 method in the range of 200–400 nm using Lab-sphere Inc.-USA make UV-Transmittance Analyser with the following equation for UPF [39]:

U PF =

∑

/ 400 400 E λ Sλ Δλ ∑ E λ Sλ Tλ Δλ 290 290

(2)

where, Eλ is the relative erythemal spectral effectiveness (unitless), S λ is the solar ultraviolet radiation (UVR) spectral irradiance in W.m−2 .nm−1 , T λ is the measured spectral transmission of the fabric, Δλ is the bandwidth in millimetres, and λ is the wavelength in nanometer (nm). Total UV radiation that can reach earth, 94% is UV-A and 6% is UV-B, where the latter is most harmful [40–42] and need. UV-protection in this zone of UV-B radiation.

3.4 Anti-microbial Property The antibacterial property of selective cotton fabric swatches was assessed according to the AATCC 100-2012 method for textiles (equivalent to GB/T 20,944.3-2008). using two selected strains (i) Klebsiella pneumoniae: AATCC 4352 (Gram + ve bacteria) and (ii) Staphylococcus aureus: AATCC 6538 (Gram −ve bacteria) using

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petri plates incubated at 37 °C for 24 h taking pictures of petri plates before and after 24 h. After completing 24 h incubation, the counting of bacteria colonies was carried out, and the reduction of bacteria % for both strains was calculated as follows: R (%) = (A − B)/A × 100%

(3)

where R is the rate of % bacterial reduction and A and B are the numbers of Counted visual bacterial colonies from (i) untreated control fabric samples and (ii) Treated/ dyed and/or finished fabric samples, respectively.

3.5 UV-Vis Spectroscopy, HPLC, and FTIR Scan for Catechu and Gall Nut UV-Vis Absorption Spectra. UV-Vis spectral curves of catechu extracts were taken and the wavelength of maximum absorption was determined using a 1% diluted solution of purified catechu, by evaluating the photometric scan of wavelength vs absorbency at 200–700 nm using Hitachi-Japan Make (Model: U-2000) UV-Vis absorbance spectrophotometer. High-Pressure Liquid Chromatography (HPLC). HPLC scan of alkaline aqueous extract of catechu after neutralizing the solution at pH 6–7 was taken, with 15 min run time on column C 18 maintaining a flow rate of 1 mL, and chromatogram peaks found at 255 nm were recorded. FTIR Spectra. Fourier transforms infrared (FTIR) spectroscopic spectra of catechu powder and differently treated and untreated cotton fabric were studied and recorded using Perkin Elmer make SPECTRUM-TWO model FTIR instrument. The FTIR spectra were taken at 500–4000 cm−1 preparing and mounting samples by the standard KBR pellets method of FTIR scanning.

3.6 Study of Surface Topology by SEM Micrograms The surface topology was examined and recorded for selected samples of cotton fabric surface at requisite magnifications. The fibre taken out from the selective cotton fabric samples was prepared for SEM study with gold–palladium alloy coating and was examined in a scanning electron microscope recorder with a resolution of 1.0 nm (15 kV) with accelerating voltage 0.1–30 kV.

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4 Results and Discussion 4.1 Characterization of Catechu UV-Vis spectra. Figure 1 shows the obtained UV -Vis spectra of purified Catechu Powder, having few small sharp peaks at 290–300 nm, besides a broader hump at 370 nm at the UV zone and indicating the presence of specific identification peaks of UV-Vis spectra of catechu at 445 nm nearly matching with earlier reported identifiable peaks mentioned in IS-Standard-IS 17211:2019: Textile Dyestuffs-Catechu-Identification. HPLC Spectra. HPLC of aqueous extract of catechu purified dye powder was taken in a specific solvent system: 50:50 (MeOH: deionized water) in 15 min run time and the chromatogram was recorded and shown in Fig. 2, showing two distinct peaks at 255 nm (Fig. 2) showing the main peak of largest height at 2.5 min for and other peaks at 1.8 min, matching with HPLC chromatogram of catechu showing said two characteristic peaks at 255 nm showing peak heights at 1.8 min and 2.5 min run time matching with reported identifiable HPLC chromatogram peaks of catechu mentioned in IS-Standard IS 17211:2019: Textile Dyestuffs-Catechu-Identification. Sometimes, another small peak is seen at 4.5 min, which is absent in this sample. This HPLC plot (Fig. 2) of catechu extract thus clearly indicates the presence of two separate colouring compounds in catechu which is reflected by two sharp peaks responsible (i) for Catechin and (ii) Quercitrin as catechol tannic acid. FTIR Spectra. The FTIR spectrum of purified catechu (Acacia catechu) dye powder (Fig. 3) shows a broader peak at 3450 cm−1 representing the free phenolicOH groups in abundance [22]. A small peak at 1648 cm−1 and a sharp peak at 1028 cm−1 and a small peak at 1742 cm−1 are characterized peaks of the C = C and C = O–CH3 ester group and aliphatic acetoxy group of saponins [43]. A small sharp peak at 1610 cm−1 as well as at 1490 cm−1 , are the characteristic peaks of catechin and catechol (one of the major colour components present in catechu). Peaks at

Fig. 1 UV-Vis spectra of aqueous extract of purified catechu

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Fig. 2 HPLC chromatogram of aqueous extract of purified Acacia catechu at 255 nm

Fig. 3 FTIR of purified Acacia catechu dye powder (in KBr) after soxhelting and drying

at1502–1517 cm−1 show aromatic ring C = C stretching [44]. The peaks of the free phenolic O–H and the vibration of the aromatic ring of condensed tannin in catechu are indicated by the small peak at 1450–1460 cm−1 [45], as shown in Fig. 3.

4.2 UV-Vis Spectra of Eucalyptus Leaves UV-Vis wavelength scan of purified and diluted solution of (i) 0.1% water-based aqueous extract of eucalyptus leaves and (ii) 0.1% aqua-ethanolic extract of eucalyptus leaves and (iii) 0.1% extracted solution of microwave irradiated (10 min) aqueous extract of eucalyptus leaves, were separately obtained by wavelength scanning in a Hitachi make-U-2000 model of UV-Vis absorbance spectro-photometer 190 to s1100 nm and are shown in Fig. 4a–c. Figure 4a (for aqueous extract of eucalyptus leaves) shows two sharp but smaller peaks at 334 and 370 nm, showing a separate presence of condensed gallo-tannins and ellagitannins by the small peak at 334 nm and the presence of hydrolysable

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(a)

(b)

(c)

Fig. 4 a UV-Vis spectra of aqueous extract of eucalyptus leaves. b UV-Vis spectra for an aquaethanolic extract of eucalyptus leaves. c UV-Vis spectra of microwave irradiated aqueous extract of eucalyptus leaves

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tannins by another small peak at 370 nm, both at UV zone and one large hump of peak starting at 380 nm in UV zone and shows the peak at 418/420 nm as λmax in visible zone ending at 440 nm, with another flatter hump at 460 nm in the visible zone. Figure 4b (for an aqua-ethanolic extract of eucalyptus leaves) shows a large clear and sharp peak at 256 nm showing a strong presence of UV-absorption character in UV zone, indicating a total combined large peak of all types of tannins present in it merged at UV zone showing large peak height at 256 nm and spread over at 220–370 nm, besides a larger flat hump at 460 nm, which can be considered as λmax and another very small notch like a small flatter peak at 664 nm in the visible zone for other minor components. Figure 4c (for microwave irradiated extract of eucalyptus leaves), multiple UVabsorber small peaks at 213–224 nm and a sharp shoulder peak at 257 nm in the UV zone, and no sharp or noticeable peaks are obtained in the visible zone, though a small notch appears at 460 nm.

4.3 Effects of Mordanting Method on Colour of Catechu-Dyed Cotton Effects of 15% single mordant for each of, harda, gall nut, and alum, were compared with effects of varying dosages of dual pre-bio-mordanting applied in sequence on cotton fabrics before 30% catechu dyeing at earlier determined optimised dyeing conditions. Relevant data are given in Table 1. Effects of Dual combinations of mordanting (harda + alum or gall nut + alum combinations in the ratio of 75:25, 50:50, and 25:75) were found to render much better colour-strength than the use of any single mordant studied. Colour yield is found highest for 15% alum single pre-mordanting as compared to the K/S result obtained with 15% gall nut single pre-mordanting or 15% single harda pre-mordanting. The said tannin-rich bio-mordanting assistants like harda and gall nut singly cannot increase dye uptake to the desired level, when applied in single, as compared to alum as a natural resource-based metallic mordant. While gall nut or harda when applied in combination with alum, as dual pre mordants, catechu natural dye molecules can be anchored to both the mordants and also to cellulose fibre through the aluminium metal of alum as well as by tannin/tannic acid residue of gall nut or chebulinic acid residue of harda, due to the possible formation of (cotton fibre-gall nut-alum-catechu dye) coordinated giant complex formation utilizing unsatisfied 3 valences of aluminium, besides some H-bonding possibility. Comparing results of ΔE, ΔL, Δa, and Δb and finally CDI values, it is indicated that higher uniformity in colour yield and other colour parameters with lower/ minimum CDI values is observed for gall nut single pre-mordanting (which shows lower and minimum CDI values than harda and alum single mordant). All alum single pre-mordanted cotton samples show higher CDI values indicating lesser dye/colour

0.02

0.06

1.01

0.80

0.62

0.73

0.91

1.32

1.75

1.80

Bleached cotton

Alum (15% sol.)

Harda (15% sol.)

Gall nut (15% sol.)

Harda + Alum (25:75)-Total 15%

Harda + Alum (50:50)-Total15%

Harda + Alum (75:25)-Total 15%

Gall nut + Alum (25:75)-Total 15%

Gall nut + Alum (50:50)-Total15%

Gall nut + Alum (75:25)-Total 15%

K/S (Mordanted)

Mordant*

10.20

10.83

12.19

9.86

10.08

10.48

7.45

7.10

10.07

–

K/S Catechu (30%)

5.41

3.55

2.54

2.89

3.50

3.86

3.24

3.26

4.35

–

ΔE*

3.6

2.14

0.76

2.55

2.68

3.79

2.14

1.97

−2.02

−2.36

−2.39

−0.55

−1.03

3.49

1.57

−0.38

−1.25

−2.00

1.82

3.29

1.84

−1.44

−1.21

−1.91

1.84

2.18

2.37

−0.57 −0.56

−2.57

−2.56

0.52

–

ΔC* 2.33

–

Δb* −2.68

– 2.14

−1.96

Δa*

–

ΔL*

Table 1 Effects of single and dual pre-bio-mordanting on colour parameters for 30% catechu-dyed cotton fabrics

2.33

2.05

2.38

0.63

1.18

−3.76

1.09

−0.56

2.73

–

ΔH*

2.48

2.38

2.41

2.81

2.79

3.34

2.36

2.62

2.54

–

MI (LABD)

1.54

1.66

1.74

0.53

0.77

2.36

0.68

0.27

2.00

–

CDI

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uniformity. The highest K/S values were obtained for alum single pre-mordanting followed by 30% catechu dyeing by 15% alum concentration, while 15% gall nut and 15% harda as a single pre-mordanted sample show lesser K/S values than alum at comparable mordant and dyeing conditions but both harda and gall nut shows lesser CDI values indicating better dyeing uniformity than alum. Later, for 30% catechu dyeing with the combination of alum + gall nut and alum + harda dual pre-biomordanting applied in sequence one by one separately at comparable conditions of mordanting and dyeing with 30% catechu extract, 15% overall application of alum + gall nut (25:75 ratio) combination gives best dyeing results, with highest K/S value and better dyeing uniformity with lesser CDI values than comparable dosages of overall 15% application of harda + alum (25:75 ratio) or any other combinations of single or dual pre-bio-mordanting used. This difference can be viewed as an effect of the higher tannin content of gall nut than that of harda though both show similar CDI values. Moreover, harda/gall nut containing tannates, and polyphenolic hydroxyl compounds along with containing gallic acid/ellagic acids, etc., which can combine with cations of alum and form an insoluble complex in situ in cellulosic fabric and act as a catcher for water-soluble alum preventing its partial aqueous solubilisation and loss of alum in dye bath water. Hence, resultant shade depth (K/S value) is found to be higher for this dual pre-bio-mordanting combination of alum either with harda or gall nut. However, between gall nut and harda, gall nut show to some extent better results of colour yield and overall better colour fastness results (as shown in Table 2) than that for harda, at comparable conditions of pre-mordanting and dyeing, due to higher tannin content of gall nut. Corresponding results of colour fastness ratings as shown in Table 2, indicate moderate colour fastness to washing (3 or 3–4 rating) and moderate colour fastness Table 2 Colour fastness ratings for 30% catechu-dyed cotton fabrics with varying concentrations of bio-mordants Mordant and dye used

Colour fastness rating for Wash

Light

LOD

ST

Harda-15% + Catechu 30%

2–3

2–3

Gall Nut-15% + Catechu 30%

3

3

K-Al-15% + Catechu 30%

3

15% [Gall Nut + K-Al (25:75)] + Catechu-30%

3–4

15% [Gall Nut + K-Al (50:50)] + Catechu-30%

Rubbing Dry

Wet

2–3

2–3

2

3

3

2–3

3

2–3

3

2–3

3–4

3

3–4

3

3–4

3–4

3

3–4

3

15% [Gall Nut + K-Al (75:25)] + Catechu-30%

3–4

3–4

2–3

3

2–3

15% [Harda + K-Al (25:75)] + Catechu-30%

3

2–3

2–3

2–3

2–3

15% [Harda + K-Al (50:50)] + Catechu-30%

3–4

3

2–3

3

2–3

15% [Harda + K-Al (75:25)] + Catechu-30%

3

3

3

3

2–3

*

K- Al = Potash alum mordant

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to sunlight, and poor to moderate colour fastness to rubbing (2–3 or 3 ratings) irrespective of types of mordants used, i.e., alum/gall nut or harda bio -mordants used. But critical comparison amongst all the single and double pre-mordants used, the relative order of performance of overall all-round colour fastness results, are in the following increasing order: only harda ≥ only gall nut ≥ only alum ≥ harda + alum ≥ gall nut + alum Therefore, a 15% total gall nut plus alum combination (25:75 ratio) of dual biopre-mordanting applied in sequence on cotton renders good results of colour yield and a moderate to good rating for overall all-round colour fastness to wash, light, and rubbing, to obtain a darker and uniform dark brown shade on cotton fabric.

4.4 Reaction Mechanism and FTIR Study for the Analysis of Fibre-Mordant Dye System Catechu has catechin and quercetin as major colour components with numerous aromatic-phenolic OH groups as mordant able having –OH, –NH2, –COOH groups) that enable the catechu dye to form a stable coordination complex with a metal ion and tannate anions combined attached cellulosic fibre in associating help of tannates, where tannates of bio-mordants additionally help to form a bigger giant complex of (cotton fibre-gall nut-alum-catechin from dye) like a Grignard compound, as shown later in 4th step of reaction mechanism given in Fig. 5, to understand it clearly.

Fig. 5 Mechanism of giant complex formation amongst potash alum and gall nut and polyphenolic mordant able catechin extracted of catechu natural dye applied on cotton cellulose

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4.5 FTIR Analysis Figure 6 shows four FTIR spectra S1, S2, S3, and S4, which illustrate all common peaks of untreated/treated/dyed cotton cellulose are known from the literature, and hence those are not discussed except the minor and major differences in peaks amongst these 4 numbers of FTIR spectra. All these four FTIR spectra shown in Fig. 6 are quite similar, except for some minute differences/variations observed. Based on actual chemical interactions that happened some minor differences in relevant FTIR spectra are noted for evidencing resultant functional groups formed. A finer analysis of FTIR spectra S1 to S4 in Fig. 6, indicates that two small new peaks at 993 cm−1 and also at 1004 cm−1 [46] appear in both FTIR spectra S2 and S4 only, as evidence of the formation of AlO as new functionality, in alum pre-mordanted cotton and also in alum + gall nut dual pre-mordanted and catechu dyed cotton, confirming (cellulose fibre-o-al-gall nut-catechu dye) coordinate complex formation via Al-O functionality, (which is not present in FTIR spectra S1 and S2), supporting the reaction mechanism in Fig. 5. The peak at 810 cm−1 is distinct in FTIR spectra S1 due to vibrations of the –CH2 –OH group of celluloses, which is found to reduce in intensity and shifted to 815 cm−1 in FTIR spectra S2, and the same is reduced distinctly in FTIR spectra S3 & S4 when gall nut based –COOH groups of gallic acid/ellagic acid groups are

Fig. 6 FTIR spectra (S1): sourced and bleached cotton; (S2): scoured and bleached cotton treated with alum mordanting (S3): scoured and bleached cotton pre-mordanted with gall nut bio-mordant and (S4): scoured and bleached cotton fabric pre-mordanted with overall 15% alum + gall nut (25:75) and dyed with 30% catechu

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attached to the primary alcohol groups of cellulose, reducing the vibrations of the –CH2 –OH group of celluloses, in FTIR spectra S3 and S4, The peak at 1238 cm−1 is not present in FTIR spectra S1, but that is found to appear in FTIR spectra S3 and S4, which are due to –C–N and N–H stretching vibration of protein/amide/amino residue present in gall nut extract. Hence, the peak at 1238 cm−1 appears prominently in FTIR spectra S3 and S4 for gall nut-treated and alum + gall nut-treated cotton fabric dyed with catechu. The increase in peak height in the reverse hump-like peak at 2360–2400 cm−1 , reveals increased –C–N and –N–H stretching in FTIR S3 and S4, due to increased protein/amide/amino residue, attached in both gall nut treated cotton and alum + gall nut treated cotton dyed with catechu, as found in both FTIR spectra S3 and S4. A tiny new peak at 1610 cm−1 appaered only in FTIR spectra S4 (alum + gall-nut dual pre-bio-mordanted cotton dyed with catechu) and is not present in FTIR SpectraS1, S2, and S3, confirms the presence of catechin, as the main colourant compound of catechu, confirming the formation of (cellulose fibre-o–al-gall nut-catechin of catechu dye) complex, supporting also the 4th step of reaction mechanism, shown in Fig. 5.

4.6 Effect of Post-dyeing Finishing Treatments with Natural and Eco-Safe Finishing Agents Effects of different post-treatments are studied here using different natural finishing agents and eco-safe finishing agents on catechu-dyed cotton fabrics after the said pre-mordanting followed by dyeing with 30% catechu extract at optimized dyeing conditions on its colour parameters and colour-fastness and relevant results are shown in Table 3. Effect of Post Treatments with Chitosan and Nano-chitosan and CTAB on Colour Parameters. Relevant results on K/S values and related parameters and colour fastness to washing, light, and rubbing are shown in Table 3 for selective posttreatments with 2% Chitosan + 0.4% citric acid or lemon juice (citrates /ascorbates as a catalyst) or with 0.2% nano-chitosan solution +0.04% lemon juice and also with an alkaline solution of 2% CTAB -as a dye fixer) by padding (100% wet pick up)-drying (100 °C for 5 min)-curing (120 °C for 3 min) process. Chitosan may be readily reactive by utilizing the functionality of its primary amino group and the primary and secondary hydroxyl groups. The primary amino group of chitosan in an acidic medium/catalyst forms a cationic derivative generating –NH3 + functionality in an acidic medium in the presence of citric acid (CA) or lemon juice and it can therefore function as a natural cationic dye-fixer to enhance washing fastness of anionic natural dyes like catechin in catechu extract. In between chitosan and nano chitosan, a similar effect is obtained by a much lesser amount of chitosan by use of 1/10th nan-chitosan instead of normal chitosan, which is assumed as an effect of highly spreading power over the fibre surface in

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Table 3 Effect of post-dyeing finishing treatments with natural and eco-safe chemical finishing agents on catechu-dyed cotton Type of Pre- and Post-Treatments

K/S

ΔE

WF LF LOD

RF

ΔC

ΔH

MI

BI

CDI

Dry Wet

Control bleached cotton (no mordant and no dye)

0.02 –

–

–

–

–

–

–

2.83 46.85 –

Gall nut + Alum (25:75 ratio)-15% (no dyeing and no post treatment)

1.35 2.65 –

–

–

–

2.39

2.33

3.23 11.97 0.82

3

3–4 3

−0.44 2.38

2.41 10.49 0.02

Gall nut + Alum 12.19 2.54 3–4 (25:75 ratio)-15% + 30% catechu dyed (no post finish)

Post-treatment with the following agents applied on 15% (gall nut + alum -25:75) dual pre-bio-mordanted and 30% catechu dyed cotton fabric by pad dry cure process 2% Chitosan + 0.4% citric acid

10.48 3.42 4

3

2% Chitosan + 0.4% lemon juice

11.96 2.28 4

3–4 4

3–4 −2.91 −0.48 2.64 11.30 0.20

0.2% Nano-chitosan 11.43 2.26 4–5 + 0.04% lemon juice

3–4 4

4

2% CTAB (at alkaline pH)

11.10 2.81 4

3

4

3–4 −1.97 −2.00 3.39 10.45 2.33

2% ZnO + 2% HMAS polymer + 0.4% citric acid

10.76 3.48 4

4

4–5 4

−1.91

2.36 2.79 10.54 1.54

0.2% Nano-ZnO + 0.2% HMAS polymer + 0.04% citric acid

11.72 2.85 4

4

4–5 4

−1.21

1.26 2.81 12.45 1.06

10% aqueous extract 12.28 3.78 3–4 of eucalyptus leave + lemon juice (5 gpl)

4

3–4 3

10% Eucalyptus 12.12 3.87 4 leave EtOH + water extract + lemon juice (5gpl)

4–5 4

3–4 3

3–4

−3.35 −0.72 2.94 12.90 0.25

−2.83 −0.30 2.46 12.83 0.14

2.55 −4.07 3.49 10.10 1.73

2.23 −4.61 3.45

9.60 2.31

(continued)

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Table 3 (continued) ΔE

Type of Pre- and Post-Treatments

K/S

WF LF LOD

10% Eucalyptus leave micro-wave aided extract + lemon juice (5gpl)

12.24 3.84 4

2% 12.49 3.54 3–4 Supra—UV—finish (a commercial grade hydroxy benzotriazole) + 0.4% citric acid

ΔC

RF

ΔH

MI

BI

CDI

Dry Wet

4–5 4

3–4

1.90 −4.19 3.25

9.70 2.60

4

3–4

2.37 −4.80 3.60

9.44 1.99

4

** WF-Washing Fastness, LOD = Loss of Depth, LF-Light Fastness and RF-Rubbing Fastness, CA -Citric Acid and Lemon Juice-Catalyst

the form of a much thinner film of high surface areas covered due to its very fine lower particle size 100–1000 nm (average particle size being near to 275 nm) of nano-chitosan used as a nano-particle based dye fixer, it leads to having higher strike rate and reaction rate than normal chitosan. For comparative purposes, the same 30% catechu-dyed cotton fabric was also post-treated with a common commercial grade of commercial dye fixer (a quaternary ammonium compound, i.e., CTAB (Cetyl Tri Methyl Ammonium Bromide) under alkaline pH on the above said dyed cotton fabric after said gall nut + alum dual premordanting and then dyeing with catechu along with to enhance its colour fastness to washing. The comparative results of which show that improvement of washing fastness by use of 2% chitosan with 0.4% citric acid post-treatment and 2% CTAB treatment at alkaline media are at par and similar, while the use of lemon juice as a catalyst with 2% chitosan also improves ½ grade of rubbing fastness, perhaps due to less aggressive acidic action on the surface causing fewer fibre damages. However, the best results on the improvement of wash fastness up to 1 to 1.5 grade higher wash fastness (achieving colour fastness grade 4–5) and ½ grade higher rubbing fastness are obtained for the use of 0.2% nano-chitosan treatment. Scanning Electron Micrograms for the said dual mordanted and catechu-dyed cotton fabric sample and subsequent chitosan post-treated cotton fibre and nanochitosan treated cotton fibres are shown in Fig. 7, which indicate the convoluted ordinary structure of cotton fibre in SEM (a), which is partially smooth covered up in SEM (b) showing an apparent smooth coverage of chitosan deposit on convoluted cotton fibres, while SEM (c) rather shows a little bit different surface appearance with full coverage of minute nanogranular deposit of nano-chitosan with ample coverage/ masking by nano-chitosan deposit with or without agglomeration here and there on dyed cotton fibre, which perhaps is the reason for enhanced wash fastness in this case.

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(b)

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(c)

Fig. 7 Scanning electron micrograms of a catechu-dyed cotton fibre and b cotton sample-a, treated with 2% chitosan and c cotton sample-a treated with 0.2% nano-chitosan

The overall good washing fastness rendered by CTAB (a commercial eco-safe cationic dye fixing agent) as a quaternary ammonium compound in the presence of alkali, may be explained by the mechanism as shown in Fig. 8. Effect of Post-Dyeing Finishing Treatment with Normal ZnO and Nano-ZnO Powder as UV-Resistant Agent. To protect/delay UV fading, after-treatment with

Fig. 8 Mechanism of complex formation of catechu dye anion (in alkali medium) with CTAB (cationic dye fixer) for improving washing fastness of catechu dyed cotton

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a suitable preferentially UV absorbers /UV reflector compound is necessary, which can preferentially absorb or reflect UV-A (320–380 nm) [39, 40], 94% of which reaches the earth and UV-B (280–320 nm, 6% of which reaches earth) and latter is mainly responsible for fading of textiles/dyed textiles. ZnO and Nano ZnO powder dispersed in an HMAS polymer matrix with a citric acid catalyst was thus applied in the present work, as a UV-reflector finish on catechu-dyed cotton fabrics and relevant results are shown in Table 3. Relevant data in Table 3 indicate that there is some reduction in K/S values (surface colour value) probably due to the masking effect and photo bleaching action of ZnO or nano-ZnO embedded HMAS polymer film deposited on the fibre surface and show some increase in CDI values at the same time, which can be viewed as changes in scattering coefficients too due to presence numerous ZnO or nano-ZnO particles embedded under the thin HMAS polymer film. However, the effects of the reduction in colour strength are much less for the application of 0.2% nano-ZnO application than that occur for 2% Normal ZnO application. There is no such reduction in colour strength for the use of a commercial UV absorber, i.e., Supra-UV Fix-agent, which works on principles of the inherent ability of preferential UV-absorbing capacity, when treated with the said commercial UV absorber. Nanoparticles of ZnO are believed to act as a thin coated UV filter which can reflect incident UV rays, not allowing them to pass through the treated cotton fabric finished with Nano ZnO embedded in HMAS thin polymer film. However, it is assumed as a physical effect for partial prevention or reduction in passing UV light through the fabric where, numerous ZnO nano-particles act as a reflecting mirror type action as UV resistant agent, not allowing UV rays to pass though treated textiles. However, as the film of nano ZnO is not a continuous film, the UV resistant action is not obtained fully, as there are many gaps /pores in such Nano ZnO finish, where UV rays can pass from one side of the fabric to another side through gaps/pores. SEM pictures of such ZnO and nano ZnO finished catechu-dyed cotton fabric as shown in Fig. 9, will make it clearer. SEM (a) in Fig. 9, shows a simple and clear picture of unfinished dyed cotton fibre with convolutions without any ZnO treatment, while SEM (b) in Fig. 9 indicates some deposit of smooth film of HMAS polymer matrix and no irregular deposits of

(a)

(b)

(c)

(d)

Fig. 9 Scanning electron micrograms (SEM) Pictures a Pre-mordanted and 30% catechu-dyed cotton b Cotton Fibre treated with 2%ZnO + 0.4% HMAS polymer + CA c Cotton Fibre treated with 0.2% Nano-ZnO + 0.4% HMAS Polymer + 0.04% CA d Part of SEM (c) enlarged to indicate and show agglomeration creating numerous pores

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any extraneous particles as the ZnO nano-particles are well embedded in said HMAS polymer film formed, while nano-ZnO deposit shown in SEM (c) is found to have irregular surface deposit embedded in HMAS polymer film showing agglomeration here and there, which is more clearly visible when a specific part of the SEM (c) is enlarged to a higher magnification indicating the said agglomeration of nano-ZnO is observed in SEM (d) indicated by a red circle. Effect of Finishing Treatment with Differently Extracted Eucalyptus Leaves on Colour Parameters. By application of 10% extraction of differently extracted eucalyptus leaves, for comparison of the performance of eucalyptus leave extract as a natural UV-absorber compound, it is found that using post-treatment with eucalyptus leaf extract (in 50:50 EtOH and water) on catechu dyed cotton textiles after the said dual pre-bio-mordanting, light fastness results are much enhanced, at par or little higher than as observed for use of a commercial UV absorber -Supra UV Fix (Hydroxy-Benzotriazole).as observed in relevant data in Table 3. In the present work, either of the citric acid and lemon juice (containing citrate and ascorbate) was used as an acidic catalyst. Relevant data indicates that colour strength values almost remain the same for such eucalyptus extract finish, but CDI values are found to become little higher, and brightness indices are found to reduce, as compared to the same for chitosan/nano-chitosan finish and /or ZnO or nano-ZnO finish. Amongst the differently extracted Eucalyptus leaves, when the same catechu-dyed cotton fabric is post-treated with 10% of EtOH + water (50:50), i.e., aqua-ethanolic extract of eucalyptus leaves, that sample is found to be superior in rendering higher light fastness (4–5 or above), due to higher UV-absorber action of the aqua-ethanolic extract of eucalyptus leaves due to presence of more amount of eucalyptol (1–8 cineole) in an aqua-ethanolic extract of eucalyptus leaves, though colour strength results for this case is found to remain almost same, only differentiating in tonal variation being little yellower and less dark as compared to similar finished fabric obtained by other finishes as per ΔL, Δa, and Δb results, Table 3. A physical intervention was made during the extraction of the eucalyptus leaves extracted solution, by the addition of microwave ray intervention, besides normal aqueous extraction and aqua-ethanolic extraction of the same. The UV–Vis spectral scan of the three types of extracted eucalyptus solutions are shown already in Fig. 4a– c, indicating their spectral pattern and peak differences showing their UV sensitivity, clearly indicating more intense UV sensitivity with darker extract with higher colour intensity as obtained by EtOH + water based i.e., aqua-ethanolic extraction of eucalyptus leaves, rendering best results from all angles, than other two methods of the extraction process of eucalyptus. Effects of Different Natural/Eco-Safe Finishing Agents on Antibacterial properties. Relevant results in Table 4, for antibacterial properties, indicate that for both gram +ve and gram −ve bacterium, there is a 99% reduction of bacterial growth for both types of bacteria when the cotton fabric is pre-mordanted by 15% alum alone as a single mordant. This can be viewed as an effect of the known antibacterial property of fit-Kari or potash alum salt. But on dyeing, only alum premordanted cotton with 30% catechu, the antibacterial protection of alum is partially lost and reduced for both types of bacteria. This is due to the antibacterial aluminium

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metal present in alum being partly dissolved in dye bath water and partly consumed for use in the complex formation of Fibre-Mordant-Dye (FMD) complex and hence, the resistance to bacterial growth by antibacterial alum, is found to be reduced or partly lost. Application of single 15% gall nut mordanting has almost no protection (No Bacterial reduction) for gram +ve bacteria and has only 16% protection against gram +ve bacteria, due to the presence of tannin-based residues in gall nut, acting as food materials for bacteria. But only gall nut pre-mordanted cotton is when dyed with catechu, there is no change of zero bacterial reduction for gram +ve bacteria, while the presence of catechu shows some increase in protection against gram +ve bacteria up to 36%, though catechu is known to have antiseptic criteria. This may be explained as an effect of the antibacterial nature of catechu being lost, after dyeing, as catechu is also consumed in forming the Fibre-Mordant -Dye (FMD) complex. 15% total application of gall nut + alum (25:75) for dual pre-bio-mordanting without any dyeing (no catechu dyeing) shows protection of gram +ve bacteria up to 76% and protection for gram −ve bacteria is 56% bacterial reduction, which has no direct or clear cut explanations, but may be viewed as a combination of opposing effects of these two mordanting agents (alum as antibacterial and gall nut as nonantibacterial mordanting agent) finally showing a resultant effect., Table 4 and Fig. 10 (showing the corresponding petri plates). There is also a drastic decrement of bacterial reduction action for gram +ve bacteria showing no reduction and showing lower bacterial reduction values up to 46% for gram −ve bacteria, when the said total 15% application of gall nut + alum (25:75) dual pre-bio- mordanted cotton is dyed with 30% catechu, for the presence of 25% gall nut, loss of antibacterial effect of alum and catechu, consumed to form Fibre-Mordant (alum + gall nut) catechu dye complex, in this dual prebio-mordanting system, resulting poorer antimicrobial criteria, though only alum mordanting is highly antimicrobial. This may be due to the reduction of zeta potential (between +ve charged chitosan containing ammonium residue in acid media and −ve charged cell wall of bacteria), by possible combining of +ve charged chitosan by −ve charged ellagic acid and gallic acid and gall tannin present in gall nut and hence antimicrobial action of chitosan is reduced or partly lost. This assumption is supported by observed results of another set of experiments here, where the same chitosan and nano-chitosan finishes when were applied on catechu-dyed cotton fabric after only 15% alum pre-mordanting (without the use of gall nut), the antimicrobial property, i.e., bacterial reductions are found to be very high (88–98%) for both gram +ve and gram −ve bacteria for both 2% chitosan and 0.2% nano chitosan finish (excluding gall nut), Table 4 and Fig. 10 (showing the corresponding petri-plates). However, the said alum + gall nut dual pre-bio mordanted and catechu dyed cotton fabric is then finished with 2% ZnO with 02% hydroxy methyl amino silicone (HMAS) polymer with 0.4% citric acid catalyst (by pad-dry-cure process), the bacterial reduction % is noticeably good, up to 93–96% for both gram +ve and gram −ve bacterium, which again is improved further for use of 0.2% Nano-ZnO applied for post finishing with 0.2% HMAS polymer and 0.04% citric acid catalyst applied by the same process, achieving 98–99% bacterial reduction for both gram +ve and

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Table 4 Results of antibacterial (Bacterial reduction %) and UV-protection (UPF values) properties for different finishing treatments Type of post treatments/finishes

Control bleached cotton Only 15% Alum pre-mordanted (No Dyeing)

UV protection analysis (As PERAATCC-183–2004/ 2010)

Bacterial reduction % (As per AATCC-100-2012)

UV-A Tr (%)

UV-B Tr (%)

UV protection factor (UPF)

Klebsiella Pneumoniae: AATCC 4352 (Gram +ve bacteria)

Staphylococcus aureus: AATCC 6538 (Gram −ve bacteria)

14.5

16.1

05

No reduction

No reduction

10

98.0%

98.82%

84.2%

86.7%

No reduction

16.2%

No reduction

36.3%

8.93

7.61

15% Alum pre-mordanted + 30% Catechu dyed Only 15% gall nut pre-mordanted (No Dyeing)

2.72

2.55

30

15% Gall nut pre-mordanted + 30% Catechu dyed Gall nut + Alum (25:75 ratio)-15% (No Dyeing and NO finishing)

2.87

2.90

25

76.4%

56.5%

Gall nut + Alum (25:75 ratio) −15% + catechu dye-30% (No Post-dyeing finishing)

2.14

1.94

30

No reduction

46.4%

Post-treatment with different eco-safe finishing agents on 15% (gall nut + alum-25:75) dual pre-bio-mordanted and 30% catechu-dyed cotton 2% Chitosan + 0.4% citric Acid

9.56

8.26

10

No reduction

56.52%

2% Chitosan + 0.4% lemon juice

8.68

7.36

10

16.66%

56.33%

0.2% Nano-chitosan + 0.04% L lemon juice

9.57

8.47

10

56.34%

76.22%

16.60

10

85.43%

98.67%

2% CTAB (at alkaline pH)

14.3

(continued)

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Table 4 (continued) Type of post treatments/finishes

UV protection analysis (As PERAATCC-183–2004/ 2010)

Bacterial reduction % (As per AATCC-100-2012)

UV-A Tr (%)

UV-B Tr (%)

UV protection factor (UPF)

Klebsiella Pneumoniae: AATCC 4352 (Gram +ve bacteria)

Staphylococcus aureus: AATCC 6538 (Gram −ve bacteria)

2% Chitosan + 0.4% lemon juice 15% Alum pre-mordanted + 30% catechu dyed (No Gall nut)

8.68

7.36

15

88.10%

97.82%

0.2% Nano-chitosan + 0.04% lemon juice finished on only 15% alum pre-mordanted + 30% catechu dyed cotton fabric (No gall nut)

9.13

8.06

15

96.0%

98.02%

2% ZnO + 2% HMAS + 0.4% citric acid catalyst

8.7

7.4

15

93.61%

95.92%

0.2% Nano-ZnO + 0.2% HMAS + 0.04% citric acid catalyst

4.2

3.6

25

99.42%

98.80%

15% [Gall nut + alum (25:75)] + 30% catechu + 10% aqueous extract of eucalyptus leave + lemon juice (5 gpl)

3.78

3.21

40

95.34%

92.92%

15% [Gall nut + Alum (25:75)] + 30% catechu + 10% (EtOH + Water aqua-ethanolic extract of eucalyptus leave + 5gpl lemon juice

2.08

1.81

50

99.97%

99.99%

(continued)

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Table 4 (continued) Type of post treatments/finishes

UV protection analysis (As PERAATCC-183–2004/ 2010)

Bacterial reduction % (As per AATCC-100-2012)

UV-A Tr (%)

UV-B Tr (%)

UV protection factor (UPF)

Klebsiella Pneumoniae: AATCC 4352 (Gram +ve bacteria)

Staphylococcus aureus: AATCC 6538 (Gram −ve bacteria)

15% [Gall nut + Alum (25:75)] + 30% catechu + with 10% micro-wave aided extract of Eucalyptus leave + 5gpl lemon juice

3.0

2.7

45

97.92%

98.24%

15% Gall nut + Alum (25:75) + 30% catechu + 2% Supra–UV–Finish (a commercial grade hydroxy benzo-triazole) + 0.4% CA

3.48

3.2

40

No Reduction

No Reduction

*

CA-Citric acid as a catalyst

gram −ve bacterium. Similar results for the application of nano-ZnO obtained by earlier workers [47] corroborated the present findings, as one of the encouraging results for its future implementation for producing bacterial protective/antimicrobial protective cotton textiles. Moreover, there is 93–95% bacterial reduction against both gram +ve and gram −ve bacterium for finishing dual pre-mordanted and catechu-dyed fabric after finishing with 10% aqueous extract of eucalyptus leaves, while the same fabric is when post-finished with 10% EtOH + water (50:50) aqua-ethanolic extract of eucalyptus (instead of aqueous extract of eucalyptus leaves), it shows 99.9% bacterial reduction for both against gram +ve and gram −ve bacteria, showing bacterial reduction of 99.97% for gram-positive bacteria and showing 99.99% bacterial reduction of gram −ve bacteria as most excellent results vide relevant data for Table 4. The same fabric with dual pre-mordanting and dyed with 30% catechu, when finished with the application of 10% extract by microwave irradiated aqueous solution of eucalyptus leaves, it also shows a very high level of antibacterial action showing almost at par or similar level of bacterial reduction that obtained for said pre mordanted and catechu dyed cotton fabric post finished with 10% aquaethanolic extract of eucalyptus leaves, for both against gram+ve and gram −ve bacterium showing bacterial reduction of 97.91% for Klebsiella pneumoniae and

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(1a)

(1b)

(1c)

(2a)

(2b)

(2c)

(3a)

(3b)

(3c)

(4a)

(4b)

(4c)

(5a)

(5b)

(5c)

(6a)

(6b)

(6c)

Fig. 10 Photographs of petri plates of corresponding samples for the antibacterial test as per AATCC-100-2012. a Tested with Bacterial Species for 0 h b Klebsiella Pneumoniae AATCC 4352, Gram-negative bacteria, after 24 h c Staphylococcus aureus AATCC 6538, Gram-positive bacteria, after 24 h. (1) Control fabric (Standard bleached cotton control fabric: un-mordanted and undyed)—no mordanting and no dyeing. (2) 15% Only alum pre-mordanted + 30% catechu dyed cotton fabric. (3) 15% Gall nut + alum (25:75) pre-mordanted + 30% catechu dyed cotton fabric. (4) Sample post-treated with 10% eucalyptus extract (aqueous) + lemon juice (5 gpl) on 30% catechu dyed after 15% total gall nut + alum (25:75) dual pre-mordanted cotton fabric. (5) Sample Post treated with 10% eucalyptus extract (microwave irradiated) + lemon juice (5 gpl) On 30% catechu dyed after 15% total gall nut + alum (25:75) dual pre-mordanted cotton fabric (6) Sample post-treated with 10%Eucalyptus extract (by MeOH + water (50:50) + lemon juice (5gpl) on 30% catechu dyed after 15% gall nut + alum (25:75) dual pre-mordanted cotton fabric pre-mordanted + 30% catechu dyed cotton fabric. (4) Sample post-treated with 10% eucalyptus extract (aqueous) + lemon juice (5 gpl) on 30% catechu dyed after 15% total gall nut + alum (25:75) dual pre-mordanted cotton fabric. (5) Sample Post treated with 10% eucalyptus extract (microwave irradiated) + lemon juice (5 gpl) On 30% catechu dyed after 15% total gall nut + alum (25:75) dual pre-mordanted cotton fabric (6) Sample post-treated with 10% eucalyptus extract (by MeOH + water (50:50) + lemon juice (5gpl) on 30% catechu dyed after 15% gall nut + alum (25:75) dual pre-mordanted cotton fabric

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showing bacterial reduction of 98.52% for Staphylococcus aureus, vide relevant data in Table 4. Moreover, along with the UV protection criteria, the essential oil present in leaves of eucalyptus extract makes the catechu dyed and eucalyptus-finished cotton fabrics unaffected by microbes showing a high degree of antimicrobial effect too. Besides containing antioxidant eucalyptol as a major constituent, alpha-pinene, beta-pinene, etc. in the extract of eucalyptus, which are believed to be strongly antioxidant and all of these are responsible for strong resistance to bacterial growth, where an aquaethanolic extract of eucalyptus shows the highest antimicrobial protection for both gram +ve and gram −ve bacterium. Effects of Different Natural/Eco-Safe Finishing Agents on UV-Protective Finish. UV protection performance of textiles is classified as per their UV protection Factor (UPF) values where an overall UPF rating of 15–24 is considered to provide “good UV protection”, UPF rating of 25–39 is considered as “very Good UV protection”, and UPF rating as 40 or higher up to 50 is considered as “excellent UV protection [40–42], achievable by finishing treatment with different UV absorber or reflector, particularly protecting UV-B, which reaches maximum to earth. In this part of the present study, UV-protection factor (UPF values) were assessed for the above said alum + gall nut dual pre-bio-mordanted cotton fabric dyed with catechu after post-dyeing after-treated or finished with differently extracted eucalyptus leaves (by aqueous extraction, aqua-ethanolic extraction, and microwave irradiated aqueous extraction) in presence of lemon juice (containing natural citrate/ ascorbate) as an acidic catalyst and also after finished with ZnO and nano-ZnO with citric acid as catalyst. Relevant data of UV protection factor are shown in Table 4 where the UV protection Factor (UPF value) for control base cotton fabric is found as 5 only, without any mordanting, dyeing, and post-dyeing finishing. However, the maximum UPF value is obtained as 50 showing excellent UV protective performance, when the said alum + gall nut dual pre-bio-mordanted cotton fabric is dyed with catechu and is finished with 10% aqua-ethanolic, i.e., EtOH + water (50:50) extract of eucalyptus leaves with lemon juice (5gpl) as a catalyst by pad-dry-cure technique, as compared to UPF value obtained as 30 for cotton fabric pre-mordanted with 15% gall nut only (without any dyeing) or 15% only alum pre-mordanted (without any dyeing) and the same samples also after catechu dyeing under comparable conditions of post-dyeing 10% eucalyptus finish with its aqua-ethanolic extract at same and comparable conditions of treatment. vide results in Table 4. The increase of UPF values for the post-treatment finishing process with aquaethanolic extract of 10% eucalyptus leaves (E Globulus) is 5 units higher than similar post-treatment with microwave irradiated 10% eucalyptus leaves extract at comparable conditions on the said pre-mordanted-and-catechu-dyed-cotton fabric as compared to UPF value of 40 obtained for same post-treatment done on same catechu dyed cotton fabric with 10% aqueous eucalyptus leaves extract. This may be mentioned that a UPF value of 40 is also observed for the use of 2% hydroxy benzo-triazole (Supra-UV Fix, a commercial UV absorber) with 0.4% citric acid catalyst, indicating an equal at par or better performance of eucalyptus extract.

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However, when eucalyptus extract (a natural UV absorber) is treated in the presence of lemon juice by pad-dry-cure process, the –OH group of 1, 8-cineole (eucalyptol) is possibly attached by its reaction with the hydroxyl group of cellulose being able to form an ether linkage by reaction between the hydroxyl group of cellulose and hydroxyl group of the 1, 8-cineole (eucalyptol), possibly due to presence of the higher amount of eucalyptol in aqua-ethanolic extraction of eucalyptus leaves than the same for only aqueous extraction of it. Microwave irradiated extraction is expected to ionize different components at a very fast rate by bulk heating of water at a higher/sharp rise of temperature in microwave heating releasing higher active content in it for the extracted solution of microwave irradiated eucalyptus extract. Moreover, in all cases, lemon juice is used as a mild acidic catalyst, which has also UV absorbing properties due to its inherent constituents of flavonoids, coumarin and citrates, ascorbate, phenolic acids, and other minor constituents including coumarin, which is known to be a good antioxidant, which therefore can cause higher improvement in UPF value also for microwave irradiated eucalyptus extract along with UV protective action of eucalyptol and quercetin as an antioxidant showing almost at par UPF values as shown for aqua-ethanol extracted eucalyptus finish. Catechu dye extract has also some UV absorption criteria, as evidenced by UV absorption peaks at 240–255 nm in the UV–Vis spectral curve of catechu as shown in Fig. 1. Similarly, 3 nos. of UV Visible spectral scan of 3 types of extracted eucalyptus solution indicate their UV absorption criteria differentiating corresponding peak area and height under the corresponding UV–Vis spectra in the UV zone, as shown in Fig. 4a–c, where an aqua ethanolic extract of eucalyptus shows higher peak area in UV zone in the UV-Vis spectral curve of aqua-ethanolic extract of eucalyptus indicating its higher UV absorptive action. Thus, aqua ethanolic extract of 10% eucalyptus leaves may be used as a unique natural resource-based post-dyeing multiple finishing agent for cotton fabric as a natural bio-finishing agent for improving UPF up to 50 and high bacterial reduction up to 99%, for both gram +ve and gram −ve bacterium, suitable for producing antimicrobial and UV resistant protective textiles.

5 Conclusions The present study thus shows the role of chitosan post-treatment on dyed cotton as a natural resource-based wash fastness improver as a natural cationic dye fixer and the role of aqueous and EtOH extract of Eucalyptus leaves as light fastness enhancer besides the superior ability of aqua-ethanolic extracted eucalyptus to improve UPF values up to 50 and bacterial reduction of (99%) for both gram +ve and gram − ve bacteria, with high possibilities of imparting multiple functional finishing i.e. UV protection finish and antimicrobial finishes for alum + gall nut dual pre-bio mordanted cotton fabric subsequently dyed with catechu extract.

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The use of chitosan and nano-chitosan post-dyeing finishing treatment showed good improvement in washing fastness, but it could not show the expected level of antibacterial properties, due to the presence of gall nut in the said dual bio-premordanted catechu dyed cotton. Nano-ZnO finish embedded in a hydroxy amino silicone polymer shows encouraging results for improving UPF values, but still, it is below par as compared to UPF values obtained by aqua-ethanolic 10% eucalyptus leaves extract-based finish with lemon juice as a catalyst. The physical and chemical intervening mechanism of microwave irradiated extract of eucalyptus leaves and nano-ZnO finishing for the said dual pre-mordanted and catechu-dyed cotton textiles are almost at par for UPF values, but nano ZNO finish does not show antimicrobial properties to the desired level. The mechanism of dual bio pre-mordanting with alum + gall nut and subsequent catechu dyeing vis a vis post-dyeing finishing treatments with above said different natural resource-based compounds are well understood by analysis of corresponding UV-Vis, HPLC, and FTIR spectra and SEM analysis to understand the role of each of these natural finishing agents to enhanced colour fastness to light, UV-protection, and antimicrobial criteria as multi-functional properties for producing UV resistant and antimicrobial protective textiles by the above-studied routes of bio-mordanting, bio-dyeing, and bio-finishing process for cotton textiles.

References 1. Cook CC (1982) Aftertreatments for improving the fastness of dyes on textile fibre. Rev Prog Colour 12(1):78–89 2. Yadav R, Bhattacharya N (2005) Effect of acacia catechu on UV protection of cotton, polyester, and P/C blend fabrics. Colourage 52(6):49–54 3. Cristea D, Vilarem G (2006) Improving light fastness of natural dyes on cotton yarn. Dyes Pigm 70:238–244 4. Samanta P (2019) A Review on characterization and standardization for application of natural dyes on natural textiles: Part -1. Indian J Nat Fibres 5(2):53–63 5. Samanta P (2020) A review on application of natural dyes on textile fabrics and its revival strategy. In: Samanta AK, Awwad NS, Algarni HM (eds) Chemistry and technology of natural and synthetic dyes and pigments. InTech Open Publisher, London, pp 75–98 6. Gupta D (1999) Dyeing of Ratanjot dye on nylon and polyester. Colourage 46(7):35 7. Samanta AK (2020) Bio-dyes, bio-mordants, and bio-finishes: scientific analysis for their application on textiles. In: Samanta AK et al (eds) Chemistry and technology of natural and synthetic dyes and pigments. InTech Open Publisher, London, pp 03–39 8. Crews PC (1982) The influence of mordant on the lightfastness of yellow natural dyes. J Amer Inst Cons 21:43–58 9. Oda H (2001) Improvement of light fastness of natural dyes. Colour Technol 117(4):204 10. Oda H (2001) Improving light fastness of natural dyes on cotton yarn. Colour Technol 117(5):254 11. Lee JJ, Lee HH, Eom SI, Kim JP (2001) UV absorber after-treatment to improve the light fastness of natural dyes on protein fibers. Colour Technol 117(3):134 12. Micheal MN, Zaher NAE (2005) Investigation into the effect of UV/ozone treatments on the dyeing properties of natural dyes on natural fabrics. Colourage 52:83

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34. Thilagavathi T, Geetha D (2013) Low-temperature hydrothermal synthesis and characterization of ZnO nanoparticles. Indian J Phys 87:747–750 35. Samanta AK, Bhattacharyya R, Jose S (2017) Gautam Basu and Ranjana Chowdhury, Fire reatradant Finish of Jute Fabric with Nano Zinc Oxide. Cellulose 24:1143–1157 36. Shah HS, Gandhi RS (1990) Instrumental colour measurements and computer aided colour matching for textiles. Mahajan Book Distributors. Ahmedabad, pp 76–116 37. Samanta AK, Agarwal P, Singhee D, Dutta S (2009) Application of single and mixtures of red sandalwood and other natural dyes for dyeing of jute fabric: studies on colour parameters/ colour fastness and compatibility. J Text Inst 100(7):565–587 38. ISI (BIS) (1981) Handbook of textile testing SP: 15-1981. 1st edn. Bureau of Indian Standards, New Delhi, pp 221–280 39. Gies PH, Roy CR, Holmes G (2000) Ultraviolet radiation protection by clothing: comparison of in vivo and in vitro measurements. Radiat Prot Dosim 91(1–3):247–250 40. Feng XX, Zhang LL, Chen JY, Zhang JC (2007) New insights into solar UV-protectives of natural dye. J Cleaner Prod 15(4):366–372 41. Sarkar AK (2004) An evaluation of UV protection imparted by cotton fabric dyed with natural colourants. BMC Dermatol 4(15):1–8 42. Hou X, Chen X, Cheng Y, Xu H, Chen L, Yang Y (2013) Dyeing and UV-protection properties of water extracts from orange peel. J Cleaner Prod 52:410–419 43. Boruah G, Phukan AR, Kalita BB, Pandit P, Jose S (2021) Dyeing of mulberry silk using a binary combination of henna leaves and monkey jack bark. J Nat Fibres 18(2):229–237 44. Kalita BB, Jose S, Baruah S, Kalita S, Saikia SR (2019) Hibiscus sabdariffa (Roselle): a potential source of bast fiber. J Nat Fibres 16(1):49–57 45. Pandey R, Patel S, Pandit P, Nachimuthu S, Jose S (2018) Colouration of textiles using roasted peanut skin-an agro-processing residue. J Cleaner Prod 172:1319–1326 46. Djebaili K, Mekhalif Z, Boumaza A, Djelloul A (2015) XPS, FTIR, EDX, and XRD Analysis of Al2O3 Scales Grown on PM2000 Alloy. Int J Spectro. 2015:01–16 47. Kar TR, Samanta AK, Sajid M, Kaware R (2019) UV protection and antimicrobial finish on cotton khadi fabric using a mixture of nano-particles of zinc oxide and poly-hydroxy-amino methyl silicone. Text Res J 89(11):2260–2278

Optimisation of Fire-Retardant Finishing of Cotton with Ammonium Sulfamate and Sodium Stannate by User-Defined Quadratic Empirical Model Ashis Kumar Samanta, Ayan Pal, and Tapas Ranjan Kar

Abstract The present work describes the application of an eco-friendly statistically optimized fire-retardant (FR) finish on cotton woven fabric with ammonium sulfamate (AS) and sodium stannate (SS). FR properties were investigated in terms of Limiting Oxygen Index (LOI), char length, % loss of fabric tenacity along with other physical properties. Based on the preliminary experimental study, two important input variables were identified as concentration of AS and concentration of SS. By applying “Response Surface Methodology” (RSM) with the “User Defined Quadratic Empirical” (UDQE) model of the statistical experiment of design at 5 levels of each important input variable, optimum concentrations of each input variable were determined. By using a suitable regression equation, optimum FR properties were predicted. Preliminary experimental results with different concentrations of AS and SS (keeping total added chemical around 20–24%) rendered the best FR performance at 16% AS and 8% SS combination showing a synergistic with LOI value 38+ , char length around 6.6 cm with approximate 30% loss of fabric tenacity. The optimized data were nearly matching with the experimental results confirming best best-fitted statistical model for these input variables at comparable conditions of treatment. Analysis of SEM, FTIR, and TGA for optimized samples was also reported to understand the reaction mechanism. Improvement of wash stability by the addition of a small amount of zinc acetate (5%) as a catalyst was also studied. Keywords Ammonium sulfamate · Cotton · Char length · Fire-retardant finishing · LOI · Sodium stannate · Loss of fabric tenacity · UDQE

A. K. Samanta (B) · A. Pal Department of Jute and Fibre Technology, Institute of Jute Technology, University of Calcutta, Kolkata, India e-mail: [email protected] T. R. Kar Department of Khadi and Textiles, Mahatma Gandhi Institute for Rural Industrialization (MGIRI), Wardha 442001, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024 D. Gupta et al. (eds.), Functional Textiles and Clothing 2023, Springer Proceedings in Materials 42, https://doi.org/10.1007/978-981-99-9983-5_10

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1 Introduction Cotton is the most popular natural fibre and it is mostly used for manufacturing of apparel and comfortable garment due to its excellent inherent properties like drapability, breathability, dyeability, hygroscopic nature, wear’s comfort, etc. [1, 2] but it has also some negative qualities like higher moisture regain value, inferior crease resistance and easily catches fire due to low Limiting Oxygen Index (LOI) value (around of 15–19%). As a result, cellulosic polymeric material made of cotton catches fires easily with rapid rate of combustion causing frequent fire incidents with loss of human life [3]. Therefore, there is a demand for various fire-retardant (FR) finished (both durable and non-durable) cotton fabric. Harrocks and some other researchers had done an in-depth study on different conventional FR formulations and their efficiency [4–7]. Commercially most popular FR formulation for cotton was a combination of THPC and urea (phosphorous-nitrogen combination) to get a synergistic effect [8]. although this combination was susceptible to toxicity due to formaldehyde release, hence, not eco-friendly. The acidic pH required during curing for this phosphorus-containing FR compound (THPC, APO, etc.) had a negative impact on the tensile strength of cotton fabric [9]. With the help of nanotechnology, nano-zinc oxide with poly-carboxylic acid [10] and nano-zinc oxide with reactive silicone emulsion binder [11, 12] have been applied successfully on cellulosic material as ecologically green FR chemicals. A solvent-less synthesis of durable eco-friendly FR combination with ammonium salt of pentaerythritol tetra phosphoric acid has been reported by researchers [13]. Chitosan phosphate based ecologically green FR formulation for cotton textiles had been also reported [14]. A mixture of chitosan, phytic acid, and poly-carboxylic acid could also be considered a good bio-based eco-friendly FR formulation [15]. Researchers have reported that stannous (tin) and boron-based combinations could impart good FR properties in jute fabric without any toxicity [16]. Although sulfur-based compounds (e.g., sulfamic acid and its compounds) were not in the list of conventional FR formulations, research has successfully developed eco-friendly FR finishing with the help of ammonium sulfamate and urea for application on jute fabric [17]. Ammonium sulfamate along with chemicals like kaolinite, organo-layered silicate, etc., could impart fire-retardancy in polypropylene, polyamide, cotton, and woollen textile products [18–21] without any negative effect. Ammonium sulfate alone had shown a good fire-retardant property after application on cotton [22]. Lignin-based eco-friendly sodium lignin sulfonate can show self-extinguishing FR properties after application on cotton [23]. Researcher reported that calcium borate particles at the sub-micro level applied on cellulosic material had exhibited excellent FR properties [24]. Above mentioned brief literature review showed that stannous (tin)/boron-based formulation and urea/sulfamate-based formulation was already successfully applied on ligno-cellulosic fibre (e.g., jute) but stannate (tin)/sulfamate based formulation had not yet been studied, neither on cotton nor on jute. So, there is enough scope for studying a newer stannate (sodium stannate) and ammonium sulfamate-based formulation as an eco-friendly FR finish on cotton without any problem of release of

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formaldehyde or generation of smoke & corrosive gases. Hence, the present study is an attempt to study the effect of the application of varying proportion/combination of indigenously available ammonium sulfamate (AS) and sodium stannate (SS) with an aim to obtain LOI of more than 30 with a minimum loss of fabric tenacity, minimum char length and to optimize an eco-friendly newer fire-retardant formulation for cotton fabric. Improvement of wash stability with the help of zinc acetate was also reported supported by SEM, FTIR analysis. The preliminary study on the effect of FR performance on the application of different concentrations of AS and SS was studied and reported elsewhere [25]. The present work may thus be viewed as a continuation of the said preliminary study by the same group of authors to obtain the optimum formulation of AS and SS as an eco-friendly fire-retardant finish on cotton fabric with or without a fixed amount of zinc-acetate catalyst. Based on the results of a preliminary study by the same group of authors, it was felt essential to optimize the input variables, i.e., concentration of AS and SS to obtain optimum FR performances with respect to LOI, char length and % loss of fabric tenacity on cotton woven fabric using UDQE model of design of experiment under RSM.

2 Materials and Methods 2.1 Fabric Conventional H2 O2 mill bleached plain woven cotton fabric of lighter variety with aerial density (76.4 ± 3) g/sq. mt. having 291 ± 2 ends/dm, 205 ± 2 picks/dm, and thickness—(0.16 ± 0.02) mm was used in the present study.

2.2 Chemicals Analytical grade of sodium stannate (Na2 SnO3 ), ammonium sulfamate (NH4 SO3 NH2 ) with assay—98.5% and analytical grade zinc acetate [Zn(CH3 COO)2 ] from Loba Chemie Pvt. Ltd were used. Lab-grade NaOH obtained from a local supplier was also used.

3 Test Methods All the untreated (control) and treated cotton fabrics were conditioned under standard conditions at temperature (27 ± 2)°C at relative humidity (65 ± 5)% for 48 h for the following tests.

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3.1 Method of Application of FR Treatments Control fabric was dipped in an aqueous solution with varying percentages of AS for 60 min and batched at room temperature. Then AS treated cotton fabric was dipped completely in another bath in an aqueous solution of SS with varying percentages for another 60 min and batched at room temperature. Now the chemically treated fabric was padded in a laboratory padding mangle under a 2dip-2nip process adjusting wet pick up 100% using about 2.2 kg/cm2 pneumatic pressure followed by hot air drying for 5 min at 100 °C followed by curing at 150 °C for 4 min followed by NaOH washing at the end, followed by simple water washing and drying in air. To study the effect on wash stability, the control fabric was dipped in an aqueous solution with varying percentages of AS for 60 min and batched at room temperature. Then AS treated cotton fabric was dipped completely in another bath in an aqueous solution of SS with varying percentages for another 60 min and batched at room temperature. Now (AS + SS) treated fabric was further dipped and batched in a solution of 5% zinc-acetate in a pH range of 10–12 for another 60 min. Then chemically treated fabric was padded for 100% wet pick up, dried for 5 min at 100 °C, cured at 150 °C for 4 min followed by initially NaOH washing and finally washing with water and drying in air.

3.2 Mechanical Properties Tenacity and Retention of Tenacity. Fabric (warp way) tenacity expressed in cN/ Tex was measured by ravelled strip method following IS 1969-Part-I: 2009 standard in “Hounsfield” (make H-10KS) universal tensile tester, using 100 mm/min traverse speed, 200 mm gauge length at Constant Rate of Traverse (CRT) principle available at Textiles Committee, Kolkata, India. Finally, fabric tenacity was calculated using Eq. 1 Tenacity (cN/tex) =

Breaking Load (cN)   fabric wt gm/m2 × fabric width (mm)

(1)

Loss in fabric tenacity for any sample (expressed in %) was calculated using Eq. 2. Loss in fabric tenacity (%) (tenacity of untreated fabric) − (tenacity of treated fabric) × 100 = tenacity of untreated fabric

(2)

Bending Length. Bending length was measured following IS 6490: 1971 standard using SASMIRA make cantilever type of stiffness tester.

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3.3 Test of Fire-Retardant Performance Properties Test of Limiting Oxygen Index (LOI) value. A higher LOI value means a lower potential of flammability of the material. LOI value above 27 for any textile or other material is considered to be fire-retardant. LOI value was calculated following ASTM D 2863–77 standard method and was carried out at NITRA laboratory, Ghaziabad, India using “Atlas LOI tester”. Test of Char Length by 45° Inclined Plane Flammability Tester. Char length was measured following IS 11871: B: 1986 using “SDL Atlas inclined plain flammability tester at NITRA laboratory, Ghaziabad, India. Analysis of Thermal Degradation by Differential Scanning Calorimetry (DSC) and Thermo-Gravimetric Analysis (TGA). Both DSC and TGA tests were done at NITRA laboratory in Ghaziabad, India using “SDT Q 600” (for TGA) and “Q 20” (for DSC), manufacturer of both machines—TA Instruments, USA, at a temperature range from ambient (room temperature–approx. 30 °C) to 500 °C with 10 °C/ min of heating rate under inert atmospheric condition.

3.4 Fourier Transform Infrared Spectroscopy (FTIR) FTIR double beam spectrophotometer model “L1600300 Spectrum” by Perkin Elmer instrument was used with a range of 600 to 4000 cm−1 for the identification of the functional groups present in the untreated and treated cotton samples. This testing was done at IIT, Jammu, India.

3.5 Analysis of Surface Topography by Scanning Electron Microscopy (SEM) Cotton fibre samples taken out from relevant fabric are mounted on a specimen stub with double-sided adhesive tape and then subjected to coating with gold–palladium alloy using a sputter coater to avoid charging of the specimen [26]. The observations were made at an operating voltage of 20 kV using magnification of 1,000X in general or higher. It was done at BTRA Mumbai, India, using Jeo SEM analyser.

3.6 Response Surface Methodology (RSM) for Statistical Optimization of FR Recipe By careful analysis of different designs of experiment models like Box-Behnken design, Central Composite response surface designs, User Defined Quadratic Empirical (UDQE) model, etc., it was understood that in this experiment, the concentration

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of two chemicals (AS & SS) were the important variables apart from temperature and curing time. Hence, UDQE was the best-fitted model here. As per this experiment of design model, to optimize 2 input process variables, a total of 16 test runs (trial experiment) are required with 5 levels (−2, −1, 0, + 1, +2) of input variables. Here 2 input process variables i.e., the concentration of AS (x1 ) and concentration of SS (x2 ) were planned to optimize three (3) important output resultant variables–LOI (Y1 ), char length (Y2 ), and loss of fabric tenacity % (Y3 ). This model is based on the second-order following polynomial regression model of quadratic response surface equation to obtain an optimum value of each output variable (Y1 , Y2 & Y3 ) separately and can be mathematically represented by Eq. 3 Yi = β0 +

i=k  i=1

βi xi +

i=k 

βii xi2

i=1

+

j=k i=k  

βi j xi x j (Regression Equation)

(3)

i=1 j=1

In the present work, only two input variables (x1 and x2 ) were taken for optimization. So, for every output resultant variable, the above quadratic regression equation may be represented in simplified form as follows: Yi = β0 + β1 (x1 ) + β2 (x2 ) + β11 (x1 )2 + β22 (x2 )2 + β12 (x1. x2 )

(4)

where Y is the process response or output (dependent) variable. β0 is the constant of the regression equation. β1, β2 are the first-order primary (linear) regression coefficient for AS (x1 ), and concentration of SS (x2 ), β11 , β22 are the quadratic (squared) regression coefficient for x1 , x2, and β12 are the interaction regression coefficient for x1 , x2 . The values of the constant and regression coefficients are obtained from the analysis of variances (ANOVA) data. The work like ANOVA calculation, regression coefficient value calculation, etc. are carried out using computer-aided statistical tool-based software (Minitab 21.2, trial version).

4 Results and Discussion 4.1 Preliminary Study The primary objective of this present work is to get an optimized ecologically greener fire-retardant formulation from AS and SS to contribute to optimized fire-retardant performance. Application of varying concentrations of AS and SS were applied on cotton fabrics and their fire-retardant performance was examined where it had been found that AS and SS individually were equally effective for incorporating fire-retardant-related properties on cotton fabric achieving LOI values 30–32. From the preliminary study, it was found that when controlled fabric was treated with a combination of varying concentrations of AS and SS keeping the sum of total FR chemicals application to

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24% to achieve a target LOI value of 32–35 or better having loss of fabric tenacity within 25–30% and char length to about 7 cm. Corresponding results were shown in Table 1. Table 1 Physical and fire-related properties of control fabric and FR-treated fabrics Physical properties

Flammability property

Expt. no

Chemical treatment

% Loss in fabric tenacity (± range)

Elongation %

Bending length (in cm)

LOI

1

Control Cotton fabric

–

27.12

1.76

2

Cotton fabric treated with AS (24%)

15 (±3.5)

24.44

3

Cotton fabric treated with SS (24%)

08 (±3.0)

4

Cotton fabric treated with AS (4%) and SS (20%)

5

45° inclined flammability tests Flame spread time (in s)

After glow time (in s)

Char length (in cm)

18.00

32

18

Completely burnt

2.08

30.24

21 SE

29

9.3

27.95

1.92

32.85

23 SE

31

8.2

18 (±2.5)

22.48

3.08

27.90

30 SE

28

12.4

Cotton fabric treated with AS (6%) and SS (18%)

22 (±3.0)

21.54

3.21

30.26

26 SE

33

9.2

6

Cotton fabric treated with AS (8%) and SS (16%)

24 (±3.0)

20.95

3.12

31.60

26 SE

30

8.9

7

Cotton fabric treated with AS (12%) and SS (12%)

28 (±3.5)

20.15

2.92

32.68

17 SE

30

8.6

(continued)

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Table 1 (continued) Physical properties

Flammability property

Expt. no

Chemical treatment

% Loss in fabric tenacity (± range)

Elongation %

Bending length (in cm)

LOI

8

Cotton fabric treated with AS (16%) and SS (8%)

30 (±3.0)

19.65

2.74

9

Cotton fabric treated with AS (18%) and SS (6%)

36 (±4.0)

18.24

10

Cotton fabric treated with AS (20%) and SS (4%)

40 (±4.0)

17.47

45° inclined flammability tests Flame spread time (in s)

After glow time (in s)

Char length (in cm)

38.30

12 SE

22

6.7

3.22

36.52

16 SE

26

7.8

3.40

36.48

16 SE

24

7.4

SE (self-extinguishing), AS (ammonium sulfamate), SS (sodium stannate)

From the above data in Table 1, it was observed that a noticeable fire-retardant performance property had been achieved particularly for experiment no. 8 by application of above mentioned two chemical combinations (i.e., 16% AS and 8% SS). Data in Table 1 also indicates that, after applying different combinations of AS and SS, the chemical formulation of 16%AS + 8%SS rendered experimentally the best LOI value (38.30) among all the experiments with experimentally lowest char length of 6.7 cm, but was linked with (30 ± 3.0) % loss of fabric tenacity/strength. If AS concentration was further increased beyond 16%, keeping the percentage of total FR chemicals up to 24%, there was a drop in LOI value and enhancement of char length, after glow time, flame spread time, etc. and hence, not recommended. This might be viewed as an effect of attaining an equilibrium state at the specific ratio of these two FR chemicals at 16%AS + 8%SS concentration and hence, any alterations of this ratio for AS and SS, have disturbed the equilibrium and reduced the value of LOI and other fire-retardant performance.

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4.2 Reaction Mechanism The cotton cellulose thus may react with both AS and SS during drying and curing in the following manner as shown hereunder by a suggested reaction mechanism.

Reaction 1 shows the blocking of (–CH2 OH) primary alcohol functional group of the cellulose chain by forming Cellulose Sulfamate reducing levoglucosan formation. Reaction 2 shows blocking of (–CH2 OH) primary alcohol functional group of cellulose by forming Cellulose Stannate reducing levoglucosan formation. Excess amount of AS produces more sulfamic acid (Reactions 3 and 4) and generates more H+ ions during heating/combustion and cause more loss of fabric tenacity. These H+ ions dehydrate the cellulose and promote more char formation (Reaction 5) in cellulose. Additionally, a little more SS produces more stannic hydroxide (Reaction 6,7) [27] as a fire-retardant protective layer on cotton fabric surface (on the application of heat in the presence of H+ ions developed from sulfamic acid) for better fire-retardant effect showing a synergistic effect. Cotton fabric treated with mixture of 16% AS, 8% SS and 5% zinc acetate is expected to cause further deposition of a layer agglomerated “zinc hydroxy stannate” complex as insoluble precipitated compound in addition of water-insoluble Sn(OH)2 formed and obtained from AS + SS combined treated cotton fabric is then dipped in NaOH solution forming Sn(OH)2 coating layer of on the surface, as shown in

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reaction scheme 7 and 8, expectedly improving the wash stability of this formulation too. The presence of Zn–O-vibration in FTIR of this zinc acetate catalyst treated AS + SS treated Cotton sample in Fig. 6c and extraneous agglomerated deposit of zinchydroxy stannate was also evidenced in this sample of SEM (in Fig. 4c), confirming reaction 7 and 8, as discussed later.

4.3 Statistical Optimization of FR Formulation with User-Defined Quadratic Empirical (UDQE) Model by Response Surface Methodology From the above experiments, it is observed that empirically 100% control cotton fabric treated with 16% AS + 8% SS (Table 1) provides the best fire-retardancy properties. So, as per UDQE, input independent variables are a concentration of AS (x1 ) and concentration of SS (x2 ), keeping output/dependent variables LOI (Y1 ), char length (Y2 ), and loss of fabric tenacity % (Y3 ). Five levels of input variables as per UDQE are mentioned in Table 2. The actual results of 16 experiments, as per UDQE of two input variables each with five levels of variations and the chosen output variables keeping other parameters like curing time, curing temperature etc. constant, are shown in Table 3. Response Surface Effect Analysis for LOI. ANOVA to analyse response surface effects with degree of freedom, F-value, P-value for LOI with respect to variation of AS concentration and SS concentration are shown in Table 4. Model fitness for regression is shown in Table 5 and corresponding regression coefficients along with standard errors are shown in Table 6. Test of significance for the chosen input variables was checked statistically on the F-ratio basis. With the help of software (Minitab 21.2, trial version), ANOVA data and corresponding regression coefficient values were found using UDQE quadratic regression Eq. 1 for response variable LOI. The 3D and 2D contour diagrams were plotted for LOI and shown in Fig. 1a and b. From the ANOVA analysis table (Table 4), it is found that the p-value of “Model” is much lower than the charted p-value. Hence, the model is significant. From the “Model summary” table (Table 5), a lower S value of 0.48 indicates less deviation between the input data and the regression model confirming better fitting of the model. A higher R-sq value of 98.70% also confirms the better fitting of the model for input variables. Table 2 Five levels of critical process variables for UDQE of the experiment of design Process input variables

Level −2

−1

0

+1

+2

Concentration of AS (%)

(x1 )

8

12

16

20

24

Concentration of SS (%)

(x2 )

4

6

8

10

12

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Table 3 Run table for experiment of design by UDQE at 5 levels for chosen two input variables and experimental results of three chosen output variables against all respective factorial combinations of input variables Sr. No

Value of independent input variables Experimental value of output/response/ resultant dependent variables Conc. of AS % (Level)

Conc. of SS % (Level)

LOI

Char length (cm)

Loss of fabric tenacity %

(x1 )

(x2 )

(Y1 )

(Y2 )

(Y3 )

1.

20 (+1)

6 (−1)

33.00

9.1

30

2.

16 (0)

10 (+1)

36.34

7.6

38

3.

20 (+1)

10 (+1)

35.76

7.7

37

4.

24 (+2)

8 (0)

34.09

8.7

19

5.

20 (+1)

8 (0)

36.95

7.8

40

6.

12 (−1)

10 (+1)

32.68

8.5

30

7.

24 (+2)

4 (−2)

35.69

7.4

29

8.

16 (0)

6 (−1)

37.44

7.1

36

9.

8 (−2)

8 (0)

31.50

11.0

27

10.

24 (+2)

12 (−1)

35.52

7.4

46

11.

8 (−2)

4 (−2)

30.22

10.9

24

12.

12 (−1)

8 (0)

32.47

9.2

21

13.

16 (0)

12 (−1)

35.86

7.1

34

14.

16 (0)

8 (0)

37.40

6.8

30

15.

16 (0)

8 (0)

37.60

6.7

30

16.

16 (0)

8 (0)

37.80

6.7

30

* All

the data in the table are actual experimental data against each level keeping the remaining other variables constant. AS—ammonium sulfamate; SS—sodium stannate, LOI—limiting oxygen index

Table 4 ANOVA table for LOI against varied concentrations of AS and SS Source

DF Sum of squares Mean squares F-value P-value Remarks

Model

5

121.84

20.31

74.63

0.000

Linear—AS concentration

1

39.59

39.59

145.48

0.000

Linear—SS concentration

1

6.508

6.508

23.92

0.002

Square—AS concentration

1

54.584

54.584

200.61

0.000

Square—AS concentration

1

24.494

24.494

90.02

0.000

Two-way 1 interaction AS & SS concentration

1.501

1.501

5.52

0.051

As tabulated P value is much lower than the charted value for DF-5, the model is significant

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Table 5 Model summary table for LOI S

R-sq (%)

R-sq (adj) (%)

R-sq (pred) (%)

0.48

98.70

97.77

90.90

Table 6 Regression coefficients for LOI against input process variables of AS and SS concentration Process variables

Coded coefficients

Reg coeff.

SE coeff.

T-value

P-value

Constant

β0

37.97

0.213

179.38

0.000

AS concentration

β1

1.791

0.184

12.06

0.293

SS concentration

β2

2.353

0.184

4.89

0.002

AS concentration X AS concentration

β11

−0.042

0.192

−14.16

0.000

SS concentration X SS concentration

B22

−0.114

0.192

−9.49

0.000

AS concentration X SS concentration

β12

−0.019

0.261

−2.35

0.051

From Table 6, a positive or negative value of the coefficient of regression indicates that each input variables have an effect (positive or negative) on the output response variable (LOI). It may be noted that a variable has a significant effect if the coefficient of regression value is greater than twice its standard error coefficient value but non-significant results should also be taken into account for calculations. By analysis of Tables 4 and 6, it is observed that the constant of the regression (β0 ), the linear regression coefficient for AS concentration (β1 ), and the linear regression coefficient for SS concentration (β2 ) have a positive value indicating a direct interacting effect on response/output variable (LOI). On the contrary, the quadratic regression coefficient for AS (β11 ), the quadratic regression coefficient for SS (β22 ) and the interaction regression coefficient (β12 ) have a negative value indicating an inverse interacting effect on response/output variable (LOI). Now by replacing the constant and regression coefficients in the quadratic regression Eq. 4 with the values obtained in Table 5, the equation will be as follows: LOI = 37.97 + 1.791 ∗ AS concentration (%) + 2.353 ∗ SS concentration (%) − 0.042 ∗ AS concentration (%) ∗ AS concentration (%) − 0.114 ∗ SS concentration (%) ∗ SS concentration (%) − 0.019 ∗ AS concentration (%) ∗ SS concentration (%)

(5)

Now, putting the optimum values of concentration of AS i.e., 16% and SS concentration 8%, the predicted value of LOI generated by the RSM technique (UDQE) on the basis of Eq. 5 is as mentioned below.

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Fig. 1 a 3D Surface plot for the effect of AS & SS concentration on LOI b 2D Contour plot for the effect of AS & SS concentration on LOI

(a)

(b) LOI = 37.97 + 1.791 ∗ 0.16 + 2.353 ∗ 0.08 − 0.042 ∗ 0.16 ∗ 0.16 − 0.114 ∗ 0.08 ∗ 0.08− 0.019 ∗ 0.16 ∗ 0.08 = 38.44 The actual experimental result of LOI for 16% AS concentration and 8% SS concentration is 38.30 whereas the optimum predicted value is 38.44. Both are very nearly matching. Hence, it is confirming the fitting of this optimization process and the values obtained from the regression coefficient are found to be useful in this RSM Eq. 4 to predict the resultant LOI value efficiently.

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By using regression Eq. 2, a 3D Surface plot and a 2D contour curve for the chosen response variable LOI for input variables of AS and SS concentration are shown in Fig. 1a and b. Figure 1a and b are the 3D Surface plot diagram and 2D contour curve respectively showing the resultant effect on LOI value with respect to the combined effect of independent input variables of AS concentration and SS concentration. Figure 1a shows initially due to the combined effect of independent input variables (i.e., at AS & SS concentrations of 10% & 5% respectively), the LOI value is around 32. With the increase of concentration of each independent input variable, the LOI value is also increasing up to a critical limit showing an upward peak at the surface plot indicating a direct relationship of LOI value with independent input variables in this region. Beyond the critical limit, the LOI value is decreasing showing an inverse relationship with independent input variables. Figure 1b is the contour curve representing a 3D surface diagram in 2D form. The lines in the diagram Fig. 1b represent the Z-axis, i.e., LOI value at different concentrations of independent input variables. This diagram shows that the optimum LOI value is 38+ and can be achieved at around 16% AS concentration and 8% SS concentration. By analysing the surface plot (Fig. 1a) it is observed that during increasing values of independent input variables (i.e., the concentration of AS & SS), an equilibrium condition is achieved showing a peak of maximum LOI value. By analysing the contour curve (Fig. 1b), the values of independent input variables (i.e., concentration of AS & SS) at the equilibrium condition are found to be approximately 16% AS concentration and 8% SS concentration which matches closely with experimental results at comparable conditions. Response Surface Effect Analysis for Char Length. ANOVA analysis, model fitness for regression with corresponding regression coefficients of input variables, and standard errors for char length is shown in Tables 7, 8, and 9, respectively. Similarly, 3D and 2D contour diagrams were plotted for response variable char length. From the ANOVA analysis table (Table 7), it is found that the p-value of “Model” is much lower than the charted p-value. Hence, the model is significant. Lower S value and higher R-sq value (Table 8) confirm the better fitting of the model for input variables. Now by replacing the constant and regression coefficients in the quadratic regression equation 4 with the values obtained in Table 9, the RSM equation will be as follows: Char Length = 6.873 − 0.993 ∗ AS concentration (%) − 0.992 ∗ SS concentration (%) + 0.024 ∗ AS concentration (%) ∗ AS concentration (%) + 0.058 ∗ SS concentration (%) ∗ SS concentration (%) − 0.002 ∗ AS concentration (%) ∗ SS concentration (%)

(6)

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Table 7 ANOVA table for char length against variation of concentration of AS and SS Source

DF

Sum of squares

Mean squares

F value

P value

Remarks

Model

5

44.969

7.493

Linear—AS concentration

1

22.741

22.741

905.11

0.000

2746.97

0.000

As tabulated P value is much lower than the charted value for DF-5, the model is significant

Linear—SS concentration

1

0.094

0.094

11.32

0.012

Square—AS concentration

1

17.221

17.221

2080.12

0.000

Square—AS concentration

1

6.347

6.347

766.66

0.000

Two-way interaction AS & SS concentration

1

0.023

0.023

2.72

0.143

Table 8 Model summary table for fit regression model for char length S

R-sq

R-sq (adj)

R-sq (pred)

0.69

91.98%

86.25%

83.06%

Table 9 Regression coefficients for char length against input process variables of AS concentration and SS concentration Process variables

Coded coefficients

Reg coeff.

SE coeff.

T-value

P-value

Constant

β0

6.873

0.037

179.92

0.000

AS concentration

β1

−0.993

0.032

−52.41

0.000

SS concentration

β2

−0.992

0.032

−3.36

0.012

AS concentration X AS concentration

β11

0.024

0.034

45.61

0.000

SS concentration X SS concentration

β22

0.058

0.034

27.69

0.000

SS concentration X SS concentration

β12

0.002

0.046

1.65

0.143

The optimum char length will be: Char Length = 6.673 − 0.993 ∗ 0.16 − 0.992 ∗ 0.08 + 0.024 ∗ 0.16 ∗ 0.16 + 0.058 ∗ 0.08 ∗ 0.08 − 0.002 ∗ 0.16 ∗ 0.08 = 6.64 cm.

From the experimental data, char length at 16%AS concentration and 8% SS concentration, is 6.70 cm whereas the optimum predicted value is 6.63 cm. Both are very nearly matching and the model is best fitted for char length.

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Figure 2a shows initially due to the combined effect of independent input variables (i.e., at AS & SS concentration of 10% & 5% respectively), char length value is around 10 cm. With an increase in concentration of each independent input variables, char length value drops dropping up to a critical limit showing a downward crest at the surface plot indicating an inverse relationship with independent input variables. Beyond the critical value, char length is increasing showing a direct relationship with the combined effect of independent input variables. Figure 2b is the contour curve representing the surface diagram in which the optimum char length value is found less than 7+ cm at around 16% AS concentration and 8% SS concentration. Response Surface Effect Analysis for Loss % of Fabric Tenacity. ANOVA analysis, model fitness for regression, and corresponding regression coefficients of Fig. 2 a 3D surface plot for the effect of AS & SS concentration on char length b 2D contour plot for the effect of AS & SS concentration on char length

(a)

(b)

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input variables along with standard errors for another response variable, i.e., % loss of fabric tenacity are shown in Tables 10, 11, and 12, respectively. Similarly, 3D and 2D contour diagrams were plotted for the response variable, i.e., % loss of fabric tenacity to analyse the effects of two chosen input variables on this resultant output variable are shown in Fig. 3a and b. From the ANOVA analysis table (Table 10), it is found that the p-value of “Model” is much lower than the charted p-value. Hence, the model is significant. Lower S value Table 10 ANOVA table for % loss of fabric tenacity against varied concentrations of AS and SS Source

DF Sum of squares Mean squares F value P value Remarks

Model

5

504.62

84.10

133.92

0.000

Linear—AS concentration

1

215.05

215.05

342.44

0.000

Linear—SS concentration

1

221.95

221.95

353.43

0.000

Square—AS concentration

1

23.82

23.82

37.93

0.000

Square—AS concentration

1

4.92

4.92

7.84

0.027

Two-way 1 interaction AS & SS concentration

32.60

32.60

51.92

0.000

As tabulated P value is much lower than charted value for DF-5, the model is Significant

Table 11 Model summary table for fit regression model for % loss of fabric tenacity S

R-sq (%)

R-sq (adj) (%)

R-sq (pred) (%)

2.71

87.17

78.01

80.45

Table 12 Regression coefficients for % loss of fabric tenacity against two input process variables of AS concentration and SS concentration Process variables

Coded coefficients

Reg coeff.

SE coeff.

T-value

Pvalue

Constant

β0

30.400

0.3024

92.63

0.000

AS concentration

β1

−0.964

0.280

18.51

0.000

SS concentration

β2

0.706

0.280

18.80

0.000

AS concentration X AS concentration

β11

0.028

0.292

6.16

0.000

SS concentration X SS concentration

β22

−0.051

0.292

−2.80

0.027

SS concentration X SS concentration

β12

0.089

0.396

7.21

0.000

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(a)

(b) Fig. 3 a 3D Surface plot for effect of AS & SS concentration on % loss in fabric tenacity b 2D Contour plot for effect of AS & SS concentration on % loss in fabric tenacity

and higher R-sq value (Table 11), confirm the better fitting of the model for input variables. Now by replacing the constant and regression coefficients in the quadratic regression equation 4 with the values obtained in Table 8, the RSM equation will be as follows: % loss of fabric tenacity = 30.40 − 0.964 ∗ AS concentration (%) + 0.706 ∗ SS concentration (%) + 0.028 ∗ AS concentration (%) ∗ AS concentration(%) − 0.051 ∗ SS concentration (%) ∗ SS concentration(%) + 0.089 ∗ AS concentration (%) ∗ SS concentration(%)

The optimum % loss of fabric tenacity will be: % loss of fabric tenacity = 30.40 − 0.964 ∗ 0.16 + 0.706 ∗ 0.08

(7)

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+ 0.28 ∗ 0.16 ∗ 0.16 − 0.051 ∗ 0.08 ∗ 0.08 + 0.089 ∗ 0.16 ∗ 0.08 = 30.30 From the experimental data, the % loss of fabric tenacity at 16%AS concentration and 8% SS concentration is 30 whereas the optimum predicted value is 30.30. Both are very nearly matching and the model is best fitted for % loss of fabric tenacity. Figure 3a shows initially due to the combined effect of independent input variables (i.e., at AS & SS concentration of 10% & 5%, respectively), the % loss in fabric tenacity value is around 25. With the increase of concentration of each independent input variable, the % loss in fabric tenacity value is increasing slowly indicating a direct relationship of % loss in fabric tenacity with independent input variables. Figure 3b is the contour curve representing the surface diagram in which the % loss in fabric tenacity value at 16% AS concentration and 8%SS concentration is around 30.

5 Analysis of Surface Topography by SEM Two micrograms shown in Fig. 4a, b represent control cotton fabric, cotton fabric treated with a mixture of 16% AS and 8% SS. Figure ure4(c) represents cotton fabric treated with a mixture of 16% AS, 8% SS, and 5% zinc acetate. Untreated cotton fabric (Fig. 4a) appears to be smooth on the surface with a few etching dots and very fine crack marks which may have arisen during oxidation in bleaching. Cotton fabric treated with a mixture of 16% AS and 8% SS (Fig. 4b) depicts a super fine but smooth layer of stannic hydroxide, cellulose stannate, and cellulose sulfamate on the surface suppressing the dots and crack lines of control fabric confirming reaction scheme 1, 2, 6 and 7. Cotton fabric treated with a mixture of 16% AS, 8% SS and 5% zinc acetate (Fig. 4c) shows agglomerated deposits of “zinc hydroxy stannate” [28] precipitate in addition to coating layer on the surface confirming the reaction scheme 7 and 8, improving the wash stability too.

(a)

(b)

(c)

Fig. 4 SEM images a Untreated cotton (control) fabric b Cotton fabric treated with a mixture of 16% AS and 8% SS c Cotton fabric treated with 16% AS + 8% SS + 5% zinc acetate

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6 Analysis of Thermal Degradation Table 13 shows the change in sample weight during an increase in temperature. Figure 5a is the TGA thermogram of control (cotton) fabric and Fig. 5b is the TGA thermogram of cotton fabric treated with 16% AS and 8% SS. Table 13 Weight loss percentage and residual char percentage during TGA analysis with respect to temperature increase Temperature range (°C)

Weight loss percentage (%) Control fabric

Cotton fabric treated with 16% AS + 8% SS

(a)

(b)

Ambient to 200

5.04

4.93

200–250

0.26

27.01

250–300

1.78

11.21

300–350

21.84

4.26

350–400

55.13

4.39

400–500

2.8

6.06

13.15

41.79

Residual char %

Fig. 5 TGA thermogram of (a) Untreated cotton fabric and (b) Cotton fabric treated with 16% AS and 8% SS

Optimisation of Fire-Retardant Finishing of Cotton with Ammonium …

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From data of Table 13, it is observed that cotton fabric had produced around 13.15% residual char while cotton fabric sample treated with 16% AS and 8% SS had produced around 41.79% residual char, i.e., there is a 28.64% increase in residual char indicating good fire-retardancy performance. From the TGA thermogram (Fig. 5), it was observed that the thermal decomposition of cotton fabric has initiated at around 330 °C while the thermal decomposition of cotton fabric sample treated with 16% AS and 8% SS had started at around 240 °C, i.e., there was lowering of decomposition temperature by around 90 °C indicating change of pyrolysis route of cellulose by limiting producing flammable volatile (levoglucosan) [29] indicating a good fire-retardancy performance.

7 Analysis of FTIR Spectra In the FTIR spectra shown in Fig. 6, a common peak is observed in the 3200– 3350 cm−1 zone for both control fabric (Fig. 6a) and cotton fabric treated with 16% AS and 8% SS (Fig. 6b) indicating vibration of –OH stretching of cellulose due to formation of hydrogen bond between cotton and moisture. Flattening in peak in 3200–3350 cm−1 zone for Fig. 6b may be due to a change in the number of -OH groups by the formation of cellulose-stannate-hydroxide [Cell-CH2 -Sn(OH)6 ] and

Fig. 6 FTIR spectra for a control fabric, b cotton fabric treated with 16% AS and 8% SS and c cotton fabric treated with 16% AS, 8% SS, and 5% zinc acetate

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stannic hydroxide [Sn(OH)6 ]. Change in peak height in Fig. 6b at 530–590 cm−1 attributed to Sn–OH or SnO2 vibration. For Fig. 6b, the addition and change of peak at 1450 cm−1 indicate O–H/C–H bending and C–O stretching, respectively. Peak in between 460 and 650 cm−1 with a top at 610 cm−1 and peak in 900–1200 cm−1 zone with a crest at 1030 cm−1 confirms vibration of sulfamate (−SO3 NH2 ) group for Fig. 6b. Changes in peak in the 1300 to 1400 cm−1 zone with a sharp peak at 1400 cm−1 have arisen due to stretching vibration of both primary and secondary amines. Change of peak in between 1400 and 1700 cm−1 zone indicated degradation of cellulose polymeric chain under acidic conditions. In Fig. 6c, peaks at 450 and 1720 cm−1 indicate Zn–O vibration due to the formation of zinc-hydroxy-stannate along with the possibility of the formation of traces of residual Zn–OH or ZnO2 present in the zinc-acetate treated AS + SS applied cotton fabric.

8 Analysis of Wash Stability with or Without Using Zn-Acetate Catalyst For analysis of wash stability, cotton fabric was treated with 16% AS + 8% SS without catalyst and with 5% zinc acetate as catalyst. Both the fabrics were washed with 0.1% non-ionic soap solution with a liquor ratio of 1:50 for 30 min at 40 °C as per IS 687: 1978 standard and the resultant LOI values are shown in Table 14. From this table, it is observed that the initial LOI value is almost at par for both treatments, but after the application of zinc acetate catalyst, the wash stability increases up to 10 wash cycles. Reduction/loss of LOI value on successive cycles of washing, for zinc acetate catalysed AS + SS fire-retardant treated cotton fabric is much lower than the fabric treated with 16% AS + 8% SS without application of catalyst and washed up to 10 cycles (Table 14). This higher wash stability for zinc acetate catalysed AS + SS fire-retardant treated fabric may be considered as an effect of the formation of insitu insoluble precipitate as an additional protective layer of agglomerated insoluble precipitate of “zinc hydroxy stannate” deposited on the treated fabric, as evidenced both from analysis of SEM in (Fig. 4c) and presence of Zn–O vibration in FTIR curve in Fig. 6, IR spectra (c), discussed in earlier part. Table 14 Wash stability of fire-retardancy performance with respect to LOI for fabric treated with and without zinc acetate Test parameter

Cotton fabric treated with AS Cotton fabric treated with AS (16%) and SS (8%) (self-catalyst) (16%) and SS (8%) + 5% zinc acetate

LOI

Without wash

38.30

38.00

2 washes

37.80

37.80

4 washes

36.00

37.20

8 washes

33.50

35.40

10 washes

32.70

35.00

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9 Conclusions A preliminary study with varying concentrations of AS and SS revealed that best fire-retardancy performance could be achieved by a combination of 16% AS + 8% SS applied in sequence. After this treatment, the LOI value was 38.30, char length was 6.70 cm, flame spread time was 12 s, and afterglow time was 22 s with a 30% loss of fabric tenacity. There is no need for an additional acidic catalyst in this reaction as it appears to be self-catalysed by sulfamic acid obtained from AS on heating. There is an increase of around 27–28% more char formation and a change of pyrolysis route after the said treatment on cotton fabric indicating good fire-retardant properties. Finally, it can be concluded that the wash stability of this fire-retardant finish can be improved by the additional use of a 5% zinc-acetate catalyst.

References 1. Jeon H, Lee J, Park J, Kang C (2021) Eco-friendly, less toxic and washing durable flameretardant finishing for cotton fabrics using a blocked isocyanate and 3-(dimethylphosphone)N-methylopropionamide. Mater Chem Phys 273:125149 2. Ren J, Wang C, Zhang X, Carey T et al (2017) Environmentally-friendly conductive cotton fabric as flexible strain sensor based on hot press reduced graphene oxide. Carbon 111:622–630 3. Cheng XW, Zhang C, Jin WJ, Huang YT et al (2021) Facile preparation of a sustainable and reactive flame retardant for silk fabric using plant extracts. Ind Crops Prod 171:113966 4. Harrocks AR (1986) Flame-retardant finishing of textiles. Rev Prog Color 16:62–101 5. Harrocks AR (1996) Developments in flame retardants for heat and fire resistance textiles-the role of char formation and intumescence. Polym Degrad Stab 54:143–154 6. Weil ED, Levchick SV (2008) Flame retardants in commercial use of development for textiles. J Fire Sci 26(3):243–281 7. Ramachandran T, Vellingiri K, Kannan MSS (2005) A comparative study of durable flameretardant finish on cotton fabrics. IE(I) J Text Eng 85:29–32 8. Patil VM, Desmukh A (2012) Some studies of temporary and permanent flame retardants on 100% cotton fabric. In: Textile and fashion proceedings on RMUTP international conference. SAGE, India, pp 272–278 9. Basak S, Samanta KK, Chattopadhyay SK (2015) Fire retardant property of cotton fabric treated with herbal extract. J Text Inst 106(12):1338–1347 10. El-Hady MMA, Farouk A, Sharaf S (2013) Flame retardancy and UV protection of cotton-based fabrics using nano ZnO and polycarboxylic acids. Carbohydr Polym 92(1):400–406 11. Samanta AK, Bhattacharya R, Jose S, Basu G, Chowdhury R (2017) Fire retardant finish of jute fabric with nano zinc oxide. Cellulose 24(2):1143–1157 12. Thilagavathi T, Geetha D (2013) Low-temperature hydrothermal synthesis and characterization of ZnO nanoparticles. Indian J Phys 87(8):787–750 13. Jia Y, Hu Y, Zhengn D et al (2017) Synthesis and evaluation of an efficient, durable, and environmentally friendly flame retardant for cotton. Cellulose 24(2):1159–1170 14. El-Tahlawy K (2008) Chitosan phosphate: a new way for production of eco-friendly flameretardant cotton textiles. J Text Inst 99(3):185–191 15. Fang Y, Sun W, Li L, Wang Q (2022) Bio-based phytic acid/chitosan and polycarboxylic acid for eco-friendly flame retardant and anti-crease of cotton fabric. J Nat Fibers 19(14):8297–8308

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16. Samanta AK, Bagchi A (2017) Eco friendly fire retardant and rot resistance finishing of jute fabric using tin and boron based compound. J Inst Eng India Ser E 98(1):25–31 17. Samanta AK, Bhattacharya R, Bagchi A, Chowdhuri R (2021) Statistical optimization of ammonium sulfamate and urea-based fire protective finishing of jute fabric. In: International proceedings on functional textiles and clothing 2020. Springer, Singapore, pp 99–128 18. Tang W, Zhang S, Sun J, Gu X (2016) Flame retardancy and thermal stability of polypropylene composite containing ammonium sulfamate intercalated kaolinite. Ind Eng Chem Res 55(28):7669–7689 19. Lewin M, Zhang J, Pearce E, Gilman J (2007) Flammability of polyamide 6 using the sulfamate system and organo-layered silicate. Polym Adv Technol 18(9):737–745 20. Lewin M (1997) Flame retarding of polymers with sulfamates I sulfation of cotton and wool. J Fire Sci 15(4):263–276 21. Xia L, Wang H, Shentu B, Weng Z (2010) Ammonium sulfamate flame retarded polyamide 6: morphology and thermal degradation. Chin J Polym Sci 28(5):753–759 22. Mostashari SM, Mostashari SZ (2008) Combustion pathway of cotton fabric treated by ammonium sulfate as a flame retardant studied by TG. J Therm Anal Calorim 91(2):437–441 23. Shukla A, Sharma V, Basak S, Ali SW (2019) Sodium lignin sulfonate: a bio-macromolecule for making fire retardant cotton fabric. Cellulose 26(13):8191–8208 24. Rajpoot Y, Sharma V, Basak A, Ali W (2022) Calcium borate particles: synthesis and application on the cotton fabric as an emerging fire retardant. J Nat Fibers 19(13):5663–5675 25. Pal A, Samanta AK, Kar TR (2022) Eco-friendly fire-retardant finishing of cotton fabric with mixture of ammonium sulfamate and sodium stannate. Commun Cellulose 26. Samanta AK, Biswas SK, Mitra S, Basu G, Mahalanabis KK (2008) Chemical modification of jute fabric with ethylene glycol and its mixtures with glyoxal and amino-silicone compound under different catalyst systems for improving its textile related properties and thermal behaviour. J Polym Mate 25(2):159–183 27. El-Tahlawy K, Eid R, Sherif F, Hudso S (2008) A new route for increasing the efficiency of stannate/phosphate flame retardants on cotton. J Text Inst 99(2):157–164 28. Pan WH, Yang WJ, Wei CX, Hao LY, Lu HD, Yang W (2022) Recent advances in zinc hydroxy stannate-based flame-retardant polymer blends. Polymers 14(2175):1–15 29. Pal A, Samanta AK, Bagchi A, Samanta P, Kar TR (2020) A review on fire protective functional finishing of natural fibre based textiles: present perspective. Curr Trends Fashion Technol Text Eng 7(1):11–30

Simultaneous Dyeing and Finishing of Bio-mordanted Cotton Yamini Dhanania, Deepali Singhee, and Ashis Kumar Samanta

Abstract Natural dyeing is typically expensive because of the multi-step and lengthy process of mordanting and dyeing involved. The development of a single-step and less complex technique with added benefits that also provides functional property to the treated fabric may help to overcome this drawback. Hence, cotton fabric was simultaneously mordanted with gallnut (natural-mordant) with or without alum, dyed with babul bark (natural dye), and finished with neem leaves (Azadirachta indica) or eucalyptus leaves (Eucalyptus regnans) or ashwagandha roots (Withania somnifera) as functional finishing agents in the same bath by a single-bath two dip and two nip padding technique at 100% expression. Treatment was also done by the conventional multi-bath process for comparative purpose. All the three types of finishing agents showed improvement in the light fastness rating, UPF value, and antibacterial effect (against gram + ve and gram –ve bacteria). Resistance was higher for simultaneous application process of mordant, dye, and finishing agent by the single-bath technique as compared to sequential/conventional multi-bath method of application. Keywords Antibacterial effect · Ashwagandha roots · Cotton fabric · Eucalyptus leaves · Neem leaves · UPF

1 Introduction Herbs or plant extracts made from the roots, leaves, flowers, and seeds of several plants readily available in nature are inexpensive and non-toxic with several functional properties including antibacterial characteristics. The antibacterial extracts can be used as textile finishing agents in solvent form or as microcapsules to extend their Y. Dhanania (B) Department of Textile Science, Clothing & Fashion Studies, J.D. Birla Institute, 11 Lower Rawdon Street, Kolkata 70020, West Bengal, India e-mail: [email protected] D. Singhee · A. K. Samanta Department of Jute and Fibre Technology, Institute of Jute Technology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata, West Bengal 700 019, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024 D. Gupta et al. (eds.), Functional Textiles and Clothing 2023, Springer Proceedings in Materials 42, https://doi.org/10.1007/978-981-99-9983-5_11

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shelf life and regulate their release. These finishes don’t change the look or feel of the fabric looks, nor do they emit any chemical odor. When they are applied to textile materials, they protect both the fabric and the wearer. Several substances from natural sources that provide protection against microbes have been reported in literature. Basil (which contains eugenol as main/active component), neem (which contains limonoids including nimbinin and azadirachtin), turmeric, pomegranate, onion, aloe vera, clove oil, chitosan and sericin, and are some such organic substances having antibacterial property [1].

1.1 Neem Leaves Neem (Azadirachta indica) often called Margosa or Indian Lilac, is a member of the mahogany family and is commonly known as neem in India. It is an evergreen tree found in India, Africa, and America and is aboriginal to tropical and subtropical countries like Burma and India. The leaves and bark contain significant number of tannins and are employed in the colouring and tanning of different products [2]. Its seeds and leaves have been used as a household pesticide. Carotene, protein, carbohydrates, vitamin C, calcium, phosphorus, and magnesium are the main compounds present in neem leaves. Neem leaves mostly contain flavonoids and phytosterols (Fig. 1) like nimbin and its derivatives and polyphenols (gallic acid, catechin, epicatechin, and quercetin) that give them their colour [3, 4]. The presence of polyphenolic flavonoids like quercetin allow neem to exhibit antioxidant, anti-inflammatory, antibacterial, and antiparasitic effects. They also have the probability to be used as cheap, widely accessible, environmentally friendly antibacterial agents for textiles [5]. Several studies on the use of neem leaves as an antibacterial agent [5, 6] are available in literature. But studies on its application as a dye for silk [7], wool [8], and polyurethane fibres [9] are sporadic and limited.

1.2 Eucalyptus Leaves The fast-growing Eucalyptus tree, a member of the Myrtaceae family, can be harvested three to four years after it is planted. Every year, the eucalyptus tree acquires a new layer of bark when the outermost layer degrades and sheds itself as a waste [10]. Essential oils from eucalyptus leaves are abundantly used in the medicinal and cosmetic sectors, as well as in food colouring [11]. They also possess powerful antioxidant properties. Extracts of the bark and leaves are used for mordanting and dyeing of textiles [12, 13]. Natural tannins and polyphenols in eucalyptus range from 10–12% [14]. The bark, which is generally thrown away or burned for fuel, can be used for colouring since it contains naturally occurring tannins (ellagitannin and polyphenols), quercetin [13], and rhamnetin. About 11% tannins (mainly gallic acid and ellagic acid) and flavonoids like quercetin and rutin as well as phenolic

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(a)

(b)

(c)

(d)

(e)

(f)

Fig. 1. Chemical structure of components present neem leaves a Axadiramide A b Nimbin c Gallic acid d Quercetin e Catechin f Epicatechin

acids including caffeine, feruic, gentisic, and protocatechuic acid are present in the eucalyptus leaves (Fig. 2). Eucalyptus leaves and bark have also been reported to possess antibacterial qualities [15]. Chitosan pre-mordanted cotton fabric dyed with extract of eucalyptus leaves has reportedly exhibited good anti-bacterial and good protection character against UV light [16]. Excellent to good UPF protection property has also been reported on cotton after mordanting with different mordants (i.e., before dyeing with eucalyptus leaves) [17]. Among the different mordants, ferrous sulphate reportedly provides highest level of UPF protection.

1.3 Ashwagandha Roots Ashwagandha (Withania somnifera L.), often known as winter cherry is a member of the Solanaceae family. This plant also known as Indian ginseng has long been used as an important ingredient in Indian ayurvedic medicine. The roots of the plant are present in over 200 ayurvedic formulations and are employed to treat a variety of diseases, including nervous disorders, infections, diabetes, cancer, ulcer, immunological conditions, stress, osteoarthritis, and skin diseases [18–20]. Majority of the chemical constituents in ashwagandha including lactones, alkaloids, saponins, and anolides (Fig. 3) Singh et al. [21] have explored the use of ashwagandha for dyeing and finishing textiles for protection against microbial growth. Cotton fabric dyed with ashwagandha extract and subsequently coated with silver nanoparticles has exhibited

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(a)

(b)

(c)

(d)

Fig. 2. Chemical structure of components present in eucalyptus leaves a Gallic acid b Ellagic acid c Quercetin d Rutin

good resistance against S. aureus, E. coli, and S. typhi bacteria making them suitable for finishing biomedical cotton textiles [21, 22]. Based on the foregoing background information, an effort has been made in the current work to apply the gallnut mordant, natural dye (babul bark), and finishing

(a)

(b)

(c)

(d)

(e)

(f)

Fig. 3. Chemical structure of components present in ashwagandha roots a Withanolide A b Withanolide B c Withanolide D d Withaferin A e Withanoside I f Withanoside II

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agent (eucalyptus leaves, neem leaves, and ashwagandha roots) on cotton in a singlebath to reduce the complexity of the application process and the cost that is associated with conventional multi-bath one-by-one sequential process of application.

2 Experimental 2.1 Materials Fabric. Bleached hand-woven 100% cotton Khadi fabric with 76 GSM areal density, 0.31 ± 0.2 m fabric thickness, 86 warp yarns per inch, and 61 weft yarns per inch has been used. Natural mordant, natural dye, and natural finishing agents. Quercus infectoria, i.e., dried gallnut (natural mordant), A. Nilotica, i.e., babul bark (natural dye), and Azadirachta indica, i.e., neem leaves, Eucalyptus globulus Labill, i.e., eucalyptus leaves and Withania somnifera, i.e., ashwagandha roots as finishing agents used in the study were obtained from Kangali Charan & Sons, Kolkata. Chemical and Auxiliaries. Commercial grade alum [KAl(SO2 )4 −12H2 O] as natural metallic mordant; sodium carbonate or acetic acid for altering the pH; ethanol, conc. sulphuric acid, hydrochloric acid, ferric chloride, aluminum chloride, chloroform, ammonia, and 1% picric acid for testing were obtained from E-Merck (India); reagents (Dragendroff’s, Mayer’s and Wagner’s) were obtained from Nice Chemicals Pvt Ltd., Kolkata, India; non-ionic wetting agent (Axel NW 100) was sourced from Bharati Chemical, Kolkata, India and Amylase enzyme for desizing of cotton was obtained from Noor Enzymes Private Limited, Bandipur, West Bengal.

2.2 Method Pre-treatment of cotton fabric. Cotton fabric was desized using 2 ml/l of amylase enzyme, 5 gpl NaCl, 2 gpl non-ionic wetting agent, 1:30 MLR, for 15 min at 50– 90 °C as reported in literature [23]. The treated samples were washed in hot water for 15 min. Finally, cloth samples were washed in water and dried to a constant weight. Extraction of tannins/colourants. All materials from natural sources (gallnut as natural mordant and neem leaves, eucalyptus leaves, and ashwagandha roots as finishing agents) were mechanically pulverized into a powdered form after drying in the sun. Extraction of the several constituents from the natural source was done in aqueous conditions under varying conditions (pH—3 to 11, MLR—1:10 to 1:50, temperature—RT to 100 °C and time—15 to 120 min) and the extraction parameters were optimized on the basis of the highest optical density at maximum absorbance wavelength of the solution.

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• Dry gallnut (Quercus infectoria): pH—11, MLR—1:20, Time—45 min, Temp— 80 °C • Neem leaves (Azadirachta indica): pH—11, MLR—1:20, Time—60 min, Temp— 60 °C • Eucalyptus leaves (Eucalyptus globulus Labill.): pH—9, MLR—1:20, Time— 60 min, Temp—80 °C • Ashwagandha roots (Withania somnifera): pH—11, MLR—1:20, Time—75 min, Temp—60 °C The optimized conditions of aqueous extraction for dry gallnut established at 11 pH, 1:20 MLR, 80 °C and 45 min in a past research [24] and for powdered babul bark at 6 pH, 1:30 MLR, 45 min and 60 °C [25] were used in the present study. Mordanting with alum or gallnut separately and in combination. Cotton was pre-mordanted with alum or gallnut at different varying conditions of mordant concentrations—10–50% owf (dried weight of the material), pH—3 to 11 (addition of sodium carbonate to raise the pH and acetic acid to lower the pH), MLR—1:10 to 1:50, time—15 to 90 min and temperature—30 to 100 °C. The fabric was washed in water and air dried. Additionally, cotton was pre-mordanted with natural mordant (gallnut) and metallic mordant (alum) in combination by both sequential (multi-bath) and simultaneous (single bath) processes. In the sequential process, cotton fabric was first treated with varying concentration of gallnut extract (1–10% owf) at 11 pH, 1:20 MLR, 45 min and 80 °C followed by treatment with varying concentrations of alum (1–10% owf) at 7 pH, 1:20 MLR, 30 min and 60 °C temperature. The combination of the two mordants at no point exceeded 10% owf. Finally, the fabric was rinsed and dried in air. In case of simultaneous mordanting and dyeing, the cotton fabric was treated with both the mordants in the same bath using a total concentration of 10% (owf) of both mordants at 11 pH, 1:20 MLR, 45 min and 80 °C. After the treatment, the fabric was rinsed in water, squeezed, and dried in air. Natural dyeing with babul bark. Pre-mordanted cotton (with alum or gallnut) was dyed using babul bark at different concentration of the natural dye, pH, MLR, time and temperature. The dyed fabric was rinsed in water, and air dried followed by soaping with 1gpl non-iconic detergent for 15 min at 60 °C using 1:30 MLR. Optimization of the dyeing process variables was done on the basis of highest K/S values, other colour-related parameters, and fastness properties of cotton premordanted using gallnut (with no use of any metallic mordant) and dyed with babul bark. Sequential (multi-step) and simultaneous (single-step) mordanting of cotton with alum or gallnut, dyeing using babul bark, and finishing with different finishing agents. Gallnut/alum pre-mordanted (at optimized conditions) cotton dyed with babul bark (under optimized conditions) was separately treated for 30 min with 10% (owf) aqueous extracts of different finishing agents like neem leaves or eucalyptus leaves or ashwagandha roots by the pad-dry-cure method using 2 dip 2 nip process at a wet pick up of 100% expression. Curing was done in a clip-pin style

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hot air dryer-cum stenter for 10 min (80 °C). It was followed by curing for 4 min at 120 °C. Finally, the cotton samples were cooled in air. Lemon juice was used as an acidic catalyst (1/5th the weight of the finishing agents). For simultaneous mordanting, dyeing and finishing, cotton was treated with gallnut/alum mordant—20% (owf), babul bark natural dye—40% (owf) and finishing agents (neem leaves/eucalyptus leaves / ashwagandha roots)—10% (owf) in the same bath and then padded and cured as per the procedure mentioned above. The application process has been summarized below (Fig. 4).

●

STEP-1: Pre-treatment of cotton fabric ↓ STEP-2: Extraction of tannins / colourants from natural resources ● Bio-mordant (gallnut) as per standardised conditions [24] ● Natural dye (babul bark) as per standardised conditions [25] Finishing agents (neem leaves, eucalyptus leaves, and ashwagandha root) as conditions optimized in this study

STEP-3(a): Mordanting with only alum (by exhaust process under conditions optimized in this study) ↓ STEP-4 (a): Natural dyeing with babul bark (by exhaust process under conditions optimized in this study) ↓ STEP-5 (a): Finishing with neem leaves or eucalyptus leaves or ashwagandha roots. (by the pad-dry cure method)

↓ STEP-3(b): Mordanting with only gallnut (by exhaust process under conditions optimized in this study) ↓ STEP-3(c): Simultaneous STEP-4 (b): Natural (single-step) mordanting dyeing with babul bark (with alum or gallnut, (by exhaust process under separately), dyeing (with conditions optimized in babul bark) and finishing this study) with (neem leaves, ↓ eucalyptus leaves, and STEP-5(b): Finishing ashwagandha root extracts) with neem leaves or using the pad-dry cure eucalyptus leaves or method. ashwagandha roots. (by the pad-dry cure method) ↓ STEP-6: Testing of all Samples

Fig. 4. Schematic chart summarising the experimental method

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2.3 Testing Methods Analysis of UV–VIS spectra. The ňmax for gallnut and babul bark (0.1% aqueous extracts) were identified separately through UV-Vis spectral analysis at respectively at 410 nm and 510 nm (their corresponding ňmax ) using absorbance spectrophotometer (Hitachi-U-2000). Similarly, the wavelengths of maximum absorption for different finishing agents were identified, separately at 430 nm for neem leaves, 420 nm for eucalyptus leaves, and 400 nm for ashwagandha roots. Phytochemical analysis. Phytochemicals analysis of all extracts in water and ethanol was done using standard procedure described by Trease and Evans and Harbone [26, 27] to identify the presence of tannins, flavonoids, alkaloids, phenols, terpenoids, and saponins in the gallnut, babul bark, neem leaves, eucalyptus leaves and ashwagandha roots (Table 2). The aqueous extracts of gallnut, babul bark, neem leaves, eucalyptus leaves, and ashwagandha roots were prepared as per the optimized procedure described above, while the 45% ethanol extracts of the sample were made by putting 10 g of powdered natural finishing agent in 100 ml ethanol. Estimation of K/S and related colour-related properties. Kubelka Munk equation [28] was used to calculate the surface colour strength of dyed cotton and all other colour interaction parameters were measured using CIE-1976 formula [28]. Nimeroff and Yurow’s equation [29] was used to evaluate the General Metamerism Index (MI), and CDI, i.e., colour difference index was calculated using the newly established empirical formula [30]. Evaluation of colour fastness (wash, light, rubbing, and perspiration). Wash fastness of the dyed cotton was assessed using the Launder o Meter [IS: 7641984]; light fastness was assessed using MBTF Microscal Fade o Meter [IS: 24541984]; dry and wet rubbing colour fastness was assessed using digital crockmeter [IS: 766-1984]; and alkaline and acidic perspiration fastness were assessed using perspirometer [IS: 971-1983]. Ultraviolet protective factor (UPF). UPF of selected samples was carried out using Labsphere Inc. UV-Transmittance Analyzer following standard test method, i.e., AATCC-183-2004. Anti-bacterial property. The qualitative test process of AATCC-147-2004 [31] employing agar-diffusion process was used to determine the resisting effect of mordanted and dyed cotton fabric treated with different finishing agents against microbial activity.

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3 Results and Discussion 3.1 Phytochemical Analysis of Different Natural Resources Phytochemical analysis of extracts of gallnut (natural mordant), babul bark (natural dye), neem leaves (finishing agent), eucalyptus leaves (finishing agent), and ashwagandha roots (finishing agent) in aqueous and ethanolic media was done (Table 1). The phytochemical screening of the chemical constituents in gallnut, babul bark, neem leaves, eucalyptus leaves, and ashwagandha roots extracts indicated the existence of certain compounds in their extracts (extraction in ethanol was done only for phytochemical analysis). Flavonoids, alkaloids, tannins, terpenoids, and saponins are present in all five extracts prepared under different mediums (aqueous and ethanol) (Table 1). The extract of gallnut and babul bark showed a moderate presence of alkaloids in both the mediums. Flavonoids and tannins were present in high amounts when extraction was carried out in ethanolic medium, but it was present in moderate amounts when extraction was carried out in an aqueous medium. Terpenoids and saponin were also present in moderate amounts in both the mediums (aqueous and Table 1 Qualitative examination of the phytochemicals Phytochemical screening

Gallnut

Babul bark Neem leaves

Eucalyptus leaves

Ashwagandha roots

Aq

Et

Aq

Et

Aq

Et

Aq

Et

Aq

Et

Dragendorff’s reagent

2+

2+

2+

3+

2+

2+

2+

3+

−

2+

Mayer’s reagent

1+

2+

2+

2+

2+

2+

1+

3+

−

2+

Wagner’s reagent

2+

3+

2+

3+

2+

3+

2+

3+

1+

2+

Ammonium

2+

Aluminium chloride

2+

3+

2+

3+

2+

3+

2+

3+

−

−

3+

2+

3+

2+

3+

2+

3+

−

−

2+

3+

2+

3+

2+

3+

2+

3+

−

−

2+

2+

1+

3+

−

−

2+

3+

−

−

2+

2+

2+

2+

2+

3+

2+

3+

2+

3+

Alkaloids

Flavonoids

Tannins Ferric chloride Terpenoids Salkowski Saponins Emulsion

Aq—aqueous extract; Bt—ethanolic extract; −absence of compound; + presence in low amount; ++ presence in moderate abundance; +++ presence in high amount

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Table 2 Efficacy of alum and gallnut as mordants Conditions

K/S

Light fastness

Wash fastness

Rubbing fastness

DoS

C

CW

Dry

Wet

Alum mordanted cotton dyed with babul bark

3.5

3

2

3–4

3

3–4

3

Gallnut mordanted cotton dyed with babul bark

6.6

4

3

4–5

4

4–5

3–4

DoS—loss in depth of shade; C—Staining on cotton; CW—staining on cotswool

ethanol). Terpenoids were not present in neem leaves, but flavonoids, alkaloids, tannins, and saponins were present in considerable amounts. The ethanolic extract of eucalyptus leaves shows high abundance of alkaloids, flavonoids, tannins, terpenoids, and saponins, but its aqueous extract has a moderate presence of all these compounds. The ethanolic extract of ashwagandha roots shows a moderate presence of alkaloids. Saponins were present in high amounts in the ethanolic extract, but in moderate amounts in the aqueous extract. Ashwagandha roots extracted under both mediums of extraction do not report the presence of flavonoids, tannins, or terpenoids. With the exception of ashwagandha roots, which lack flavonoids, tannins, and terpenoids, all other extracts (gallnut, babul bark, neem leaves, and eucalyptus leaves) prepared under different mediums (aqueous and aqueous and ethanolic medium) shows presence of tannins, alkaloids, flavonoids and terpenoids, and saponins.

3.2 UV–VIS Spectral Analysis and UV–VIS Characterization UV–VIS spectra with the corresponding UV–VIS peak frequency at different wavelength (nm) of gallnut, babul bark, neem leaves, eucalyptus leaves, and ashwagandha roots aqueous extracts are shown in Fig. 5a–e and characterization of the different peaks in the visible and UV zone has been shown in Fig. 5a–e. Neem leaves. Abd El Aty et al. [32] identified three peaks at 320 nm, 370 nm, and 400 nm confirming the presence of flavonoids and other phenolic compounds. According to others [3], neem leaf extract exhibits highest absorbance between 500 and 650 nm (λmax ), where its components are complex organic compounds that may carry charge centres and are consequently susceptible to maximum absorption. Eucalyptus leaves. Absorption peaks were identified at 334 nm, 370 nm, and 418 nm. While absorption peaks around 365 nm indicate the existence of hydrolyzable tannins, absorption in the 290–340 nm region may be due to the presence of several chromophores (C = C, C = O) [33]. Eucalyptus also exhibits significant presence of gallotannins and ellagitannins as reflected by the presence of absorption peaks between 350 and 450 nm, [33] and this can probably offer good protection to the dangerous UV rays in the UV-B and UV-A region.

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(a)

(b)

(c) Fig. 5 a-e Absorbance spectra of gallnut, babul bark, neem leaves, eucalyptus leaves and ashwagandha root extracts in the UV-range (100–1100 nm) respectively

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(d)

(e) Fig. 5 (continued)

Ashwagandha roots. Ashwagandha roots show significant peak between 320 nm and 370 nm confirming the presence of antioxidants and some phenolic compounds [34]. A characteristic peak in the region (400–480 nm) is visible and may be caused by the collective oscillation of the conduction band electrons that confirms the existence of bioactive substances [35].

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3.3 Simultaneous Dyeing and Finishing of Cotton Mordanted With (a) Gallnut and (b) Alum and Dyed with Babul Bark Before Finishing with Different Natural Finishing Agents (Neem Leaves, Eucalyptus Leaves, and Ashwagandha Roots) In our earlier investigations [24, 36], the effectiveness of alum and gallnut as mordants was investigated. On cotton that has been mordanted and then dyed using babul bark extract, gallnut, a natural resource-based mordant, performs better in terms of surface colour strength and fastness (light, wash, and rubbing). This effect may be attributed to the interaction between gallnut’s higher tannin content and the presence of ellagic acid and polyphenols, which are absent in alum, and which allow for the formation of larger coordinated complexes between mordanted cotton and natural dye (babul bark), leading to improved fastness properties and higher colour strength (Table 2). Colour strength and related properties. The colour-related parameters of cotton fabric pre-mordanted with gallnut or alum and dyed with babul bark extract and finished using extracts of different finishing agents like neem leaves or eucalyptus leaves or ashwagandha roots by the simultaneous single-bath process and sequential multi-bath process is shown in Table 3. Ascending order of colour strength (K/S) of pre-mordanted cotton (with alum or gallnut) dyed with babul bark natural dye and finished with different finishing agents (neem leaves or eucalyptus leaves or ashwagandha roots) by sequential multi-bath process of application: For gallnut mordant: Eucalyptus leaves ≥ neem leaves ≥ ashwagandha roots For alum mordant: Eucalyptus leaves ≥ neem leaves ≥ ashwagandha roots. Ascending order of colour strength (K/S) of cotton simultaneous mordant (with gallnut / alum), dyed with babul bark and finished with different finishing agents (neem leaves or eucalyptus leaves or ashwagandha roots) by simultaneous single-bath process of application: For gallnut mordant: Eucalyptus leaves ≥ ashwagandha roots ≥ neem leaves For alum mordant: Eucalyptus leaves ≥ ashwagandha roots ≥ neem leaves. In all the cases, the K/S values were higher when gallnut was used as a natural mordant as compared to when alum was used as a natural metal-mordant and the same has been corroborated by Rather et al. [37]. Mordanting, dyeing, and finishing by the conventional simultaneous single-bath process gave higher colour strength (Table 3) as compared to when sequential multi-bath process of mordanting, dyeing and finishing is used (Table 3). In all cases of simultaneous single-bath process of application, the ΔE value is high (ranges between 42 and 49) indicating excellent level of colour levelness / uniformity when cotton is dyed and finished in the same bath. This result can be substantiated by the corresponding coefficient of variation values that indicate minimum variation in colour (uniformity). L* values in all the cases were found to be in the range of 50–59 indicating darker tones on the finished cotton fabric probably due to higher absorption of dye. The values of a* (redness) and b* (blueness) were always found

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Table 3 Colour-related parameters of gallnut or alum pre-mordanted cotton coloured with babul bark and finished using different finishing agents Conditions

K/S (λ max )

CV (%)

L*

a*

b*

ΔC

ΔH

ΔE

MI (LABD)

Gallnut as Mordant CONTROL Neem Eucalyptus Ashwagandha

1.3

5.1

80.4

0.4

16.9

–

–

–

–

a

6.6

13.8

46.2

13.8

20.9

8.1

−11.2

36.9

4.0

b

6.8

10.7

59.0

10.0

22.6

22.6

−12.5

42.0

5.6

a

7.1

12.2

48.1

12.3

22.1

8.4

−9.8

34.8

3.7

b

8.5

11.3

50.5

7.2

23.4

22.4

−12.9

49.0

5.1

a

6.3

10.9

51.2

13.1

20.4

7.4

−10.8

32.1

3.9

b

7.1

10.9

52.5

7.3

20.3

19.4

−11.9

45.7

4.8

Alum as Mordant 0.3

4.3

91.3

1.8

−2.3

–

–

–

–

a

4.5

22.1

52.9

13.0

19.1

20.2

−13.3

45.4

5.8

b

4.7

12.4

53.4

10.1

17.4

17.9

−10.9

44.0

5.1

a

4.7

18.7

51.1

12.3

21.4

21.7

−14.1

47.9

5.9

b

4.9

14.1

54.6

10.1

19.9

20.1

−11.7

44.1

5.4

a

3.6

17.3

56.5

11.9

16.5

17.4

−12.3

40.8

5.5

b

4.8

12.2

49.8

10.5

15.8

16.8

−10.4

46.7

5.0

CONTROL Neem Eucalyptus Ashwagandha

(a) Sequential multi-bath process (b) Simultaneous single-bath process

to be high, indicating that the cotton cloth had developed a reddish and yellowish tone, respectively. Changes in hue (H) were negative in all instances, indicating that there had been only a minor hypsochromic and bathochromic shifts in the colour/ tone and no significant change in the predominating hue. MI fluctuates from 4.8 to 5.6 showing little to no metameric influence. Colour fastness properties. Fastness of pre-mordanted cotton (with gallnut or alum) dyed with babul bark extract and finished with different extracts of different finishing agents like neem leaves, eucalyptus leaves and ashwaganda roots by the simultaneous single-bath process and sequential multi-bath process are shown in Table 4. Gallnut-mordanted cotton gave better colour fastness properties than alummordanted cotton irrespective of the process used, i.e., simultaneous single-bath process and sequential multi-bath process of application. The light fastness data (Table 5) indicated very good light fastness ranging from 6 to 7 for all cotton samples irrespective of the process of application or mordant used. An earlier study indicated a light fastness rating of only 4 [38, 39]. This may be ascribed to the development of large mordant-fibre-dye adducts/complexes. The effect can be also be corroborated with the data from UV–VIS spectra of aqueous extracts of gallnut (Fig. 5a), babul

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Table 4 Fastness of mordanted (with gallnut or alum) cotton dyed with babul bark and finished using different finishing agents Dyeing conditions

LF

Washing to ISO-II DoS C

Rub

Sweat Acidic

Alkaline

CW Dry Wet DoS C

CW DoS C

CW

Gallnut as Mordant Neem Eucalyptus

a

7

4

3–4 4

4–5

3–4

4

3–4 4

3–4

2–3 2–3

b

7

3

3–4 4

4–5

4

4

3–4 4

3

2–3 2–3

a

7

3–4

4

4

4–5

3–4

4

3–4 4

3

3

3

b

7

3

4

4

4–5

3–4

4

3–4 4

3–4

3

3

Ashwagandha a

7

3–4

4

4

4–5

3–4

4

4

3–4

3

3

b

7

3–4

4

4

4–5

3–4

4

3–4 4

3–4

3–4 3

a

6

3

4

3–4

4–5

3–4

2

3

2–3

3

3

b

7

3–4

4–5 4–5

4

3

2–3

3–4 3

3

3

3

a

6

3

3–4 4

4–5

3–4

2–3

3–4 3

2–3

3

3

b

7

3

4

4

4–5

3–4

2

3

2–3

3

3

Ashwagandha a

6

3

4

4

4

3–4

2–3

3–4 3–4

2–3

3–4 3–4

b

7

3–4

4

4

4–5

3–4

2

3–4 3–4

2–3

3–4 3–4

3–4

Alum as Mordant Neem Eucalyptus

3

3

(a) Sequential multi-bath process (b) Simultaneous single-bath process LF, Light fastness; DoS—loss in depth of shade; C—Staining on cotton; CW—staining on cotswool

bark (Fig. 5b), neem leaves (Fig. 5c), eucalyptus leaves (Fig. 5d) and ashwagandha roots (Fig. 5e) and the spectra showed presence of some small peaks in the UV region (212 nm, and 275 nm for gallnut; 240 nm, 270 nm, 290 nm for babul bark; 334 nm and 370 nm for neem leaves; 335 nm and 370 nm for eucalyptus leaves; and 325 nm, 341 nm and 392 nm for ashwagandha roots. This suggests that cotton-gallnut / alum mordant-babul bark dye may probably have formed adducts with natural finishing agents and these adducts preferentially absorb UV rays lessening the intensity of its effect on the coloured components present in the various natural sources used thereby resulting in good light fastness. This has also been described in an earlier report [24]. Fastness to washing in relation to shade depth loss irrespective of the process of application used, i.e., simultaneous single-bath process and sequential multi-bath process ranged from 3 to 3–4 (i.e., average to good) indicating variable extent of dye penetration and dye molecule fixation on the cotton fibre’s surface. In most situations, the fastness was extremely good (4 to 4–5) in terms of the extent of staining. With regard to the various finishing chemicals employed, finished cotton fabric’s dry rub fastness varied very little and is excellent, falling between 4 and 4–5 (Table 4). Good fastness to rubbing indicates the absence of loosely adhered dye on the fabric surface. On the other hand, wet rubbing fastness was to some degree less in majority of

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Table 5 Effect against bacteria by cotton simultaneously mordanted (single-bath and sequential multi-bath) with gallnut extract or alum, dyed with babul bark, and finished with different finishing agents Treatment

Inhibition zone (in mm) after 24 h E. coli

S. aureus

Scoured and bleached cotton (CONTROL)

0

0

Cotton pre-mordanted with gallnut + babul bark

5

6

Alum pre-mordanted cotton dyed + babul bark

2

3

Gallnut + neem leaves

9

12

Gallnut + eucalyptus leaves

10

12

Gallnut + ashwagandha roots

10

12

Alum + neem leaves

7

9

Alum + eucalyptus leaves

8

9

Alum + ashwagandha roots

8

9

Gallnut + neem leaves

12

15

Gallnut + eucalyptus leaves

12

15

Gallnut + ashwagandha roots

12

15

Alum neem leaves

9

11

Alum eucalyptus leaves

9

11

Alum + ashwagandha roots

9

11

Sequential Multi-Step Process

Simultaneous Single-Step Process

the cases. The wet rub fastness test using water facilitates migration of dye molecules from the surface of the fibre from where they can be easily leached out by the water present, reducing the fastness qualities. Regardless of the manner of application, acidic perspiration (loss in depth) is found to be favourable (Rating of 4) for cotton mordanted with gallnut mordant, while alkaline perspiration falls between 3 and 3–4. It was observed (Table 4) that loss in depth of colour for both acidic and alkaline mediums was slightly lower when alum was used as a mordant in case of both process of application (i.e., simultaneous single-bath process and sequential multi-bath). In the majority of cases, regardless of the mordant and application technique used, the extent of staining of adjacent cotton for acidic perspiration was comparable to that on cotswool; however, for alkaline perspiration, cotton fabric showed more staining on cotswool than cotton under similar testing conditions. This is most likely because the presence of alkali makes cotton swell, which expands the intermolecular gaps inside the fibre and makes it easier for the colour molecules to leach out of the fibre.

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3.4 Assessment of Antibacterial Properties In consideration of the demand for functional textiles with multiple uses, cotton pre-mordanted with gallnut or alum followed by dyeing with babul bark extract and finished by extracts of neem leaves or eucalyptus leaves or ashwagandha roots simultaneously in a single-bath or sequentially in a multi-bath sequence were also assessed for their property against both gram positive and negative bacteria (Table 5). On application of the finishing agent by the sequential multi-bath sequence, there was a significant improvement in the antibacterial property and the zone of inhibition increased from 5 mm (for E. coli) and 6 mm (for S. aureus) for gallnut-mordanted cotton (without finishing agent) to 9–10 mm after application of the finishing agent. The results were same when simultaneous single-bath process was used to apply the finishing agents; the zone of inhibition increased from 5 mm (for E. coli) and 6 mm (for S. aureus) for gallnut-mordanted cotton (without finishing agent) to 9– 12 mm after application of the finish. Among the sequence of process application (simultaneous single-bath process and sequential multi-bath process) used, the corresponding value for antibacterial finish (in terms of zone of inhibition) was always higher when the finishing agent was applied by the simultaneous single-bath process of mordanting, dyeing, and finishing compared to the sequential multi-bath process. Though all natural finishing agents exhibited the same degree of antibacterial finish (zone of inhibition), the corresponding zone of inhibition (antibacterial finish) for gallnut was always higher (better) than for alum, which does not contain tannins. This is also corroborated by reports that suggest that compounds containing tannins (polyphenolic compounds) exhibit antibacterial activity [40, 41]. Neem leaves are said to contain nimbin and polyphenols [3], eucalyptus leaves are said to contain polyphenols [11], and ashwagandha roots are said to contain withanolides and withaferins [21], which have antibacterial properties. Eucalyptus leaf and ashwagandha root extracts demonstrated better antibacterial effectiveness (in terms of a large zone of inhibition) than neem leaf extract, regardless of the mordant (gallnut or alum) used. However, the level of protection offered by ashwagandha roots and eucalyptus leaves was found to be the same. In comparison, the antibacterial effect was always higher (higher inhibition zone) for gram-negative than for gram-positive bacteria irrespective of the kind of mordant used (gallnut or alum) or the sequence of process stages (simultaneous single-bath process or sequential multi-bath process) used. As a result, all cotton samples dyed with babul bark and finished with aqueous extracts of various finishing agents (neem leaves, eucalyptus leaves, or ashwagandha roots) demonstrated good antibacterial function against both gram +ve and gram-ve bacteria up to 24 h of inhibition (Figs. 6 and 7).

188

S. aureus

Y. Dhanania et al.

E. coli (a)

S. aureus

E. coli (b)

S. aureus

E. coli (c)

Fig. 6. Images of petri plates for antimicrobial test against S. aureus and E. coli bacteria of cotton sequentially/concurrently treated with gallnut as natural organic mordant, babul bark as natural dyes and different natural finishing agents a neem leaves, b eucalyptus leaves and c ashwagandha roots

S. aureus

E. coli (a)

S. aureus

E. coli

S. aureus

(b)

E. coli (c)

Fig. 7. Images of petri plates for antimicrobial test against gram-positive (S. aureus) and gramnegative (E. coli) bacteria of cotton sequentially/concurrently mordanted with alum, dyed with babul bark and finished with different natural finishing agents

3.5 UV Protection Factor (UPF) of Untreated Cotton, Mordanted, Dyed, and Finished Cotton Good UPF ratings in the range of 20–45 were observed on cotton mordanted with gallnut or alum followed by dyeing with babul bark and finished with aqueous extracts of different finishing agents (neem leaves or eucalyptus leaves or ashwagandha roots). The UPF ratings were higher for simultaneous single-bath process of application of mordant, dye, and finishing agent compared to sequential multi-bath process of application. Irrespective of the process of application (simultaneous single-bath or sequential multi-bath), gallnut extract as a natural mordant imparted better UPF ratings than when alum was used as a natural metal mordant (Table 6).

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Table 6 UPF values of untreated cotton, mordanted, dyed, and finished cotton Samples

UPF (Mean)

UPF (Std. deviation)

Trans % of UV-A

Trans % UV-B

UPF rating

Bleached cotton 6.1 (CONTROL)

14.5

14.5

16.1

5

Gallnut pre-mordanted cotton

38.7

2.7

2.7

2.6

30

Alum pre-mordanted cotton

5.8

14.3

14.3

16.6

10

Cotton dyed with babul bark (no mordant)

35.2

2.9

2.9

2.9

25

Gallnut + babul 60.8 bark

2.1

2.1

1.9

35

Alum + babul bark

8.7

8.7

7.4

15

Gallnut + neem 40.84 leaves

18.34

3.08

2.93

40

Gallnut + eucalyptus leaves

31.70

4.97

3.48

3.21

40

Gallnut + ashwagandha roots

30.10

10.09

3.78

3.44

40

Alum + neem leaves

45.62

13.19

2.83

2.42

20

Alum + eucalyptus leaves

40.39

13.19

2.74

2.54

20

Alum + ashwagandha roots

29.17

8.2

3.88

3.7

20

Gallnut + neem 42.31 leaves

9.99

2.87

2.4

45

Gallnut + eucalyptus leaves

39.39

7.83

3.08

2.69

45

Gallnut + ashwagandha roots

40.69

10.07

2.6

2.47

45

Alum + neem leaves

22.88

3.95

4.88

4.57

25

13.5

Sequential Multi-Step Process

Simultaneous Single-Step Process

(continued)

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Table 6 (continued) Samples

UPF (Mean)

UPF (Std. deviation)

Trans % of UV-A

Trans % UV-B

UPF rating

Alum + eucalyptus leaves

20.72

5.15

4.99

5.04

25

Alum + ashwagandha roots

25.14

3.72

4.43

4.11

30

4 Conclusion The conditions for extraction of organic matter from the different natural finishing agents like neem leaves, eucalyptus leaves, and ashwagandha roots under aqueous conditions were optimized as mentioned below: • Neem leaves: 11 pH, 1:20 MLR, 60 min and 60 °C. • Eucalyptus leaves: 9 pH, 1:20 MLR, 75 min and 80 °C. • Ashwagandha roots: 11 pH, 1:20 MLR, 60 min and 60 °C. The chemical compounds found in gallnut, babul bark, neem leaves, and eucalyptus leaves extracts (both aqueous and ethanolic medium) all contain active ingredients like alkaloids, flavonoids, tannins, terpenoids, and saponins, with the exception of ashwagandha root extract, which is devoid of these substances. Surface colour strength and colour fastness for simultaneous single-step mordanting, dyeing, and finishing process were higher than for sequential multi-step process of application indicating that the single-stage process gives better results. It reduces the number of processing stages thereby saving on time, energy cost, water consumption, manpower consumption, and the process cost. Hence it can be considered as a more sustainable process. All cotton samples dyed with babul bark and finished with aqueous extracts of various finishing agents (neem leaves or eucalyptus leaves or ashwagandha roots) exhibited good antibacterial function against gram- + ve (S. aureus) and gram-ve (E. coli) bacteria up to 24 h of inhibition. Gallnut extract when used as a natural mordant gives better zone of inhibition compared to alum natural metal mordant irrespective of the process of application (simultaneous single-bath or sequential multi-bath) used. Good UPF ratings in the range of 20–45 were observed on mordanted cotton (with gallnut or alum) and then dyed with babul bark and finished with aqueous extracts of different finishing agents (neem leaves or eucalyptus leaves or ashwagandha roots). The UPF ratings were higher for simultaneous single-bath process of application of the mordant, dye, and finishing agent compared to the conventional multi-bath process of application. Higher chemical loss (%) in the multiple-stage process comprising of more number of stages may be seen as a cause of lower K/S, UPF, and antimicrobial rating

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191

in traditional sequential multi-stage of application compared to simultaneous singlebath process. Higher K/S, UPF, and antimicrobial rating in simultaneous single-bath process than conventional multi-bath processes can be seen as a result of increased chemical loss (%) in multi-stage processes with more stages. Gallnut extract used as a mordant irrespective of the process of application (simultaneous single-bath or sequential multi-bath) gives better UPF ratings than when alum is used as a natural-metal mordant. The entire study is based on the use of a natural plant-based mordant, natural plant-based dye, and natural plant-based finishing agents that makes the process entirely eco-friendly, sustainable, and oeko-tex certifiable.

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Functionalization of Jute to Improve Colour Yield and Fastness of Annatto Dye Ritwik Chakraborty, Ashis Kumar Samanta, and Padma Shree Vankar

Abstract Jute being an agro-renewable lignocellulosic bast fibre grown in India is mostly used in packaging applications. Functional treatments can impart value addition to the fibre for diversified applications. An endeavour was undertaken to dye jute with a natural colourant as well as to improve its antimicrobial and UV-resistance performance in the present work. Here, the jute fabric is dyed with the aqueous extract of annatto seeds after being mordanted with alum, tannic acid and stannous chloride. All these three mordants were applied on the jute fabric by padding method followed by drying in air. Mordants were applied on jute fabric individually as well as in the sequential application for dual mordanting using alum + SnCl2 and alum + tannic acid. The dyed samples were evaluated on the basis of colour strength and fastness parameters as well as their functionalized properties in terms of bacterial reduction per cent and UPF-values were evaluated. After examining the colour strength, the dyeing process variables were optimized. Wet and rubbing fastness values were found to be moderate. Jute fabrics were treated with chitosan biopolymer (0.5%, 1%, 1.5% and 2% o.w.f) and N-cetyl-N’-trimethylammonium bromide (CTAB) (1% and 2% o.w.f) to improve the wash fastness. Chitosan and CTAB improved the fastness of the dyed jute fabrics by ½ to 1 grade. Benzotriazole improved the light fastness of the dyes by 1 grade and upgraded the ultraviolet protection property of the dyed jute fabric significantly. The antimicrobial property of the dyed jute fabrics was also improved with annatto and with chitosan. Jute fabric dual-mordanted with alum and tannic acid achieved better colour strength, light fastness and UPF values than the one dual-mordanted with alum and stannous chloride. Keywords Jute · Annatto · Natural dye · Alum · Stannous chloride · Chitosan

R. Chakraborty (B) · A. K. Samanta Department of Jute and Fibre Technology, University of Calcutta, Kolkata, West Bengal, India e-mail: [email protected] P. S. Vankar Bombay Textiles Research Association, Mumbai, Maharashtra, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024 D. Gupta et al. (eds.), Functional Textiles and Clothing 2023, Springer Proceedings in Materials 42, https://doi.org/10.1007/978-981-99-9983-5_12

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1 Introduction Since pre-historic times, textiles have been dyed with natural dyes extracted from different bio-resources. The dyes were obtained mostly from plant parts. But with the invention of cost-effective synthetic dyes and with increasing demand for dyes, natural dyes gradually lost their prime position. In recent periods, a renewed interest in natural dyes has evolved owing to the potential environmental and health hazard posed by the synthetic dyes [1, 2]. Along with natural dyes, more attention has also fallen on natural fibres for the same ecological reasons. Jute is a prime natural fibre grown in India. It is mostly used in packaging materials though it has immense potential for greater diversified applications. So, if jute-based textiles are dyed with natural dyes, the end products can make a paradigm shift in jute-based products [3, 4]. Annatto is an important plant that yields dye with significant colour yield. Seeds of this plant produce dye used as a colour in food, cosmetics, textiles, etc. The main colouring component of annatto seeds is bixin and norbixin as shown in Fig. 1 — carotenoid compounds [5–7]. Though these colourants have an affinity to cellulosic materials, they produce poor to moderate fastness of colour on jute-based textiles. To overcome this, mordants are helpful. Three inorganic mordants namely, natural alum, tannic acid and stannous chloride have been chosen for this study. So, keeping all the information, the present work is designed to dye jute with annatto seeds with improved colour yield and fastness along with augmented functionalization. To add more value to the dyed jute fabrics, imparting of ultraviolet protective properties and antimicrobial properties have been considered. Improvement of UV protection also improved the light fastness property of the dyed materials. While N-Cetyl-trimethyl Ammonium Bromide (CTAB) is proven to increase the wash and rub fastness by making a complex [1,3,], benzotriazole can improve the UV protection and light fastness by absorbing UV light [1, 3, 8, 9]. Similarly, chitosan along with annatto was found to have antimicrobial properties and can be applied on cellulose-based textiles with less difficulty [10]. Fig. 1 Colouring component of annatto seeds a bixin, b norbixin

(a)

(b)

Functionalization of Jute to Improve Colour Yield and Fastness …

197

Fig. 2 Chemical structure a N-cetyl trimethyl ammonium bromide (CTAB) and b 1,2,3 benzotriazole

(a)

(b)

2 Materials and Methods 2.1 Materials Fabric. Bleached jute fabric of 47 ends/dm (warp count: 7.65 lb/spy) and 42 picks/ dm (weft count: 8.23 lb/spy), 260 g/m2 areal density was used. Natural dye. Seeds of the annatto plant (botanical name: Bixa orellena L.) were procured from M/s Kangali Charan Datta and Sons in Kolkata. Inorganic mordant. Natural alum (aluminium potassium sulphate, [KAl(SO4 )2 .12H2 O], tannic acid and stannous chloride were procured from M/s Kangali Charan Datta and Sons in Kolkata. Stannous chloride is a very strong reducing agent, but toxic for usage above 15 ppm of the weight of tin for human skin and throat. The chemical is still used in ceramics and few medicinal applications in low quantity as the catalyst which are swallowed/eaten. Hence, the use of stannous chloride was made in this work considering its strong reducing capacity (antioxidant) which is expected to reduce the fading behaviour of jute on exposure to sunlight [11]. Moreover, jute-based dyed and finished decorative fabrics are not used in products attached to human skin as they are used for home furnishing textiles. Hence, the issue of toxicity of stannous chloride is not applicable here. Auxiliary chemicals. Chitosan, N-Cetyl-trimethyl Ammonium Bromide (CTAB), LR-grade acetic acid and sodium carbonate (for adjustment of pH) and non-ionic detergent were procured from M/s Ma Kali Chemicals, Kolkata (Fig. 2).

2.2 Methods 2.2.1

Extraction of natural dye from annatto seeds

The seeds of annatto plant were pulverized into powder form and the powder was put into aqueous medium at conditions which were already optimized by Chakraborty et al. [5] for maximum colour extraction. The aqueous extract of annatto seeds was filtered.

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2.2.2

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Mordanting of jute fabric

Scoured and bleached jute fabric before dyeing was mordanted with an aqueous solution of alum with varying concentrations through the padding method. Similarly, stannous chloride and tannic acid were applied on the jute fabric in an aqueous medium. The mordanted fabrics were put to drying in air without washing.

2.2.3

Dyeing of jute fabric with aqueous extract of annatto seeds

Jute fabrics with the usage of mordants and without mordants were added to a dye bath consisting of an aqueous extract of annatto seeds. After completion of dyeing, the fabric was rinsed in cold water followed by soaping using 2 g/L of non-ionic detergent dissolved in water at 1:50 MLR at 60 °C temperature for 15 min and then it was again rinsed in cold water and dried in air.

2.2.4

Application of chitosan on fabric

Chitosan powder was put in 1% acetic acid solution to make chitosan solution of various concentrations and the solutions were kept at room temperature overnight (for 16 h). Insoluble materials were filtered out from the solution. Jute fabrics were put into the solution at 1:40 MLR and heated at 90°C for an hour. Then the fabric samples were dried in an oven at 100°C temperature for 5 min.

2.2.5

Application of CTAB and benzotriazole

1% and 2% aqueous solution of N-cetyl trimethyl ammonium bromide (CTAB) and 1% solution of benzotriazole were prepared. The dyed jute fabric samples were treated with CTAB and benzotriazole solution in padding method with almost 100% wet pick-up in the presence of 0.5% NaOH. The padded jute samples were dried and cured (heat-treated) at l00°C for 15 min in a laboratory hot air stenter in sequence.

2.2.6

Testing of dyed jute fabric

Colour strength (K/S at λ) based on reflectance value on the surface of dyed fabric evaluated by the Kubelka–Munk equation and other colour-related parameters like ΔL*, Δa*, Δb*, ΔC*, Δh* of the dyed jute fabrics were measured using Reflectance Spectrophotometer (Make: Premier Colorscan; Model: S-5100A) using Kubelka– Munk equation and CIE-Lab equations, 1976. Colour fastness to washing and rubbing of the dyed jute fabrics were measured using IS/ISO 105-C10: 2006 (reaffirmed in

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2021) and IS/ISO 105-X12: 2016 (reaffirmed in 2023) respectively. The ultraviolet protection factor of the jute fabrics was measured in between 190 and 400 nm range following AATCC-183-2004 method. The antimicrobial activity of the jute fabrics was evaluated following the AATCC-100-2004 method.

3 Results and Discussion 3.1 Effect of Mordant Application of Colour Parameters The colouring components were extracted from the pulverized powder of annatto seeds in an aqueous medium at optimized extraction conditions viz. pH 12, 95 °C temperature, 60 min time [5]. The maximum extraction is possible at alkaline conditions due to the higher solubility of carboxylic groups present at bixin and norbixin of annatto [5]. The jute fabric samples were dyed with annatto without using any mordant and then mordanting the fabric before dyeing. The mordants viz. natural alum, stannous chloride and tannic acid were applied onto the jute fabric samples separately with padding method in varying concentrations prior to their dyeing with aqueous extract of annatto seeds followed with the drying of the fabric the in air. The colour strength and related colour parameters of the dyed jute fabrics pre-mordanted with varying concentrations of both mordants are shown in Table 1. Table 1 Colour strength and other colour values of pre-mordanted dyed jute fabric Mordant concentration (o.w.f.)

K/S

ΔL*

Δa*

Δb*

ΔC*

Δh*

ΔE

Alum (5%)

3.56

−3.32

−2.17

−3.76

−2.72

2.3

5.47

Alum (10%)

3.85

−2.08

−1.27

−2.75

−2.82

3.1

3.67

Alum (15%)

3.78

−1.52

−1.47

−2.58

−2.62

3.8

3.34

Alum (20%)

3.64

−1.48

−1.57

−2.56

−2.42

3.7

3.35

SnCl2 (5%)

3.84

−2.32

−3.07

−1.41

−4.12

2.7

4.10

SnCl2 (10%)

3.92

−2.56

−2.77

−1.49

−5.02

1.8

4.06

SnCl2 (15%)

3.81

−3.12

−3.17

−1.61

−4.72

0.7

4.73

SnCl2 (20%)

3.71

−2.09

−3.57

−1.69

−4.62

2

4.47

Tannic acid (5%)

3.98

−2.79

−3.35

−2.78

−4.71

3.5

5.17

Tannic acid (10%)

4.21

−2.84

−3.01

−2.81

−4.43

3.2

5.00

Tannic acid (15%)

4.07

−2.71

−3.14

−2.94

−5.08

2.8

5.08

Tannic acid (20%)

3.92

−2.62

−3.19

−3.18

−4.92

2.7

K/S

L*

a*

b*

C*

h*

0.26

79.33

0.17

12.08

12.22

83.23

Control (bleached jute fabric)

5.21

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Table 2 Colour strength and other colour values of pre-mordanted dyed jute fabric in a dual mordanting process with alum and stannous chloride Mordant concentration (owf)

K/S

ΔL*

Δa*

Δb*

ΔC*

Δh*

ΔE

Alum (2%) + SnCl2 (8%)

3.59

−3.3

−2.66

−3.62

−4.32

3.3

5.57

Alum (4%) + SnCl2 (6%)

3.95

−1.51

−3.23

−4.14

−5.12

4.1

5.46

Alum (5%) + SnCl2 (5%)

3.88

−2.69

−2.71

−3.98

−4.72

4.8

5.52

Alum (6%) + SnCl2 (4%)

3.79

−2.29

−2.15

−3.85

−4.42

3.7

4.97

Alum (8%) + SnCl2 (2%)

3.65

−1.92

−2.23

−4.45

−4.12

3.8

5.33

Table 3 Colour strength and other colour values of dyed jute fabric in dual mordanting process with alum and tannic acid Mordant concentration (owf)

K/S

ΔL*

Δa*

Δb*

ΔC*

Δh*

ΔE

Alum (2%) + Tannic acid (8%)

3.75

−3.61

−2.88

−4.73

−6.01

4.1

6.61

Alum (4%) + Tannic acid (6%)

4.15

−2.75

−2.73

−4.82

−5.74

4.3

6.18

Alum (5%) + Tannic acid (5%)

4.31

−2.62

−2.99

−4.14

−5.61

4.9

5.74

Alum (6%) + Tannic acid (4%)

4.19

−2.56

−3.18

−3.81

−5.73

3.9

5.58

Alum (8%) + Tannic acid (2%)

3.85

−2.81

−3.15

−4.01

−5.21

4.2

5.82

As shown in Table 1, the colour strength (K/S) of the alum-mordanted dyed jute fabrics has increased with increasing add-on of alum on the jute fabric till its saturation at 10% o.w.f. add-on where the colour strength of 3.85 was achieved. The colour strength of a dyed material is the result of the colourant concentration on the fibres, and that may come as a combined action of mordants and dye molecules. Till 10% o.w.f add-on of alum on the jute fabric, dye molecules adsorbed on the fibres, and then might get desorbed to some extent what the decreasing K/S values implied. Similarly, the highest colour strength (3.92 and 4.21) of dyed jute fabrics when pre-mordanted with stannous chloride and tannic acid was achieved at 10% for both cases. As, with the experimental observation of getting the best colour strength of the dyed fabrics pre-mordanted at 10% o.w.f. mordants individually, the fabric samples were dyed with the two mordants in sequence with a total mordant concentration of 10% o.w.f. add-on. The results of the colour strength with dual mordanting are shown in Tables 2 and 3. The fabric is mordanted with 4% o.w.f. alum followed by 6% o.w.f. stannous chloride gave the best colour strength. However, the use of 5% alum with 5% tannic acid gave higher colour strength (4.31).

3.2 Optimization of Dyeing Process Variables With the finding that dual-mordant is slightly better in producing better colour strength; the process condition of the dyeing of dual-mordanted jute fabric needs

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201

to be optimized. The optimization process was carried out by measuring the colour strength with different process variables that are shown in Figs. 3, 4, 5, 6, 7 and 8. It is observed from Fig. 3 that with increasing dye concentration to 30% o.w.f, the adsorption of dye molecules also rises. Similarly, it is found that a dyeing time of 60 min, dyeing temperature of 60 °C and pH of 11 gave the best colour strength. At higher temperatures, dye molecules might get desorbed from the fibre surface whereas at low temperatures they might be absorbed on the fibres at maximum capacity due to low kinetic energy. The alkaline aqueous medium helped the dye particles get absorbed better. The liquor ratio is an important factor for dyeing. Jute being a heavy fabric, a low MLR would not help the dyes get absorbed on the fibres properly. So, an MLR of 40 is the best point to Fig. 3 Dye concentration versus colour strength a alum + stannous chloride and b alum + tannic acid

Fig. 4 Dyeing time versus colour strength a alum + stannous chloride and b alum + tannic acid

Fig. 5 Dyeing temperature versus colour strength a alum + stannous chloride and b alum + tannic acid

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Fig. 6 pH of dye bath versus colour strength a alum + stannous chloride and b alum + tannic acid

Fig. 7 MLR versus colour strength a alum + stannous chloride and b alum + tannic acid

Fig. 8 Salt concentration vs colour strength a alum + stannous chloride and b alum + tannic acid

have the highest colour strength. Lower colour strength at MLR of more than 40 can be attributed to the dilution factor. With the application of sodium chloride, it was found to get higher colour strength, as the electrolyte reduces the zeta potential of the jute fabric in an aqueous medium. A salt concentration of 30 gL−1 is the best result.

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3.3 Improvement of Fastness Properties Several researchers [3, 4] worked on the improvement of the fastness of jute fabric dyed with natural dyes. Here, also attempts were taken to improve the fastness of annatto dye jute fabric and the rub fastness values are depicted in Tables 4 and 5. Fastness values of jute fabric dyed with annatto with mordanting are poor. Table 4 reveals that the dry and wet rub fastness of jute fabric without mordanting is 2–3 and 1–2 respectively which were improved by the application of mordants. Dualmordants (alum + SnCl2 and alum + tannic acid dual-mordanting) make a complex ligand with jute fibre-mordant-dye molecules resulting in a stronger bond formation which is less susceptible to being washed off during rubbing. The dry and wet rub fastness after mordanting (in all three types) was improved to 4 and 2 respectively. CTAB, a quaternary ammonium salt made a stronger complex producing higher rub fastness. Similarly, chitosan also made a complex with fibre-dye-mordant giving a slightly better rub fastness. 1% chitosan can be considered as the best suitable for the application. The wash fastness of jute fabric dyed with annatto without mordant is poor (1–2 for change-in-colour and 2–3 for staining) as shown in Tables 6 and 7. Mordants making a bridge with dye molecules and cellulose/hemicelluloses of jute improved the wash fastness of pre-mordanted dyed fabric by ½ or 1 grade. This fastness grade Table 4 Effect of additive application on rubbing fastness of dyed fabric pre-mordanted with alum and SnCl2 Fabric sample type

Mordant typse No mordant, no additive

Alum (10% owf)

SnCl2 (10% owf)

Alum (4% owf) + SnCl2 (6% owf)

Dry

Wet

Dry

Wet

Dry

Wet

Dry

Wet

2–3

1–2

Control 2 (dual-mordanted with alum + SnCl2 , but without chitosan/ CTAB)

4

2

4

2

4

2

0.5% chitosan

4

2–3

4

2–3

4

2–3

1% chitosan

4

3

4

3

4

3

1.5% chitosan

4

2–3

4

2–3

4

2–3

2% chitosan

4

2–3

4

2–3

4

2–3

1% CTABa

4

3

4

3

4

3

2% CTABa

4–5

3

4–5

3

4–5

3

Control 1 (dyed without mordanting and without additive)

a CTAB

= N-Cetyl-trimethyl ammonium bromide

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R. Chakraborty et al.

Table 5 Effect of additive application on rubbing fastness of dyed fabric pre-mordanted with alum and tannic acid Fabric sample type

Mordant type No mordant, no additive

Alum (10% owf)

Tannic acid (10% owf)

Alum (5% owf) + Tannic acid (5% owf)

Dry

Wet

Dry

Wet

Dry

Wet

Dry

Wet

2–3

1–2

Control 2 (dual-mordanted with alum + tannic acid, but without chitosan/ CTAB)

4

2

4

3

4

3

0.5% chitosan

4

2–3

4

3–4

4

3–4

1% chitosan

4

3

4–5

4

4–5

4

1.5% chitosan

4

2–3

4

3–4

4

3–4

2% chitosan

4

2–3

4

3–4

4

3–4

1% CTAB*

4

3

4

4

4

4

2% CTAB

4–5

3

4–5

4

4–5

4

Control 1 (dyed without mordanting and without additive)

was further improved slightly (mostly ½ grade) with the application of chitosan and CTAB. The data in Tables 8 and 9 shows the improvement of light fastness of the premordanted dyed jute fabrics by one grade after their treatment with 1% benzotriazole in an acidic medium. The overall poor to average light fastness of dyed jute fabrics is attributed to the propensity of jute fibre to fade in UV light. So, benzotriazole as a UV absorber improved the light fastness property of dyed jute fabrics.

3.4 UV Protection Factor of Jute Fabrics Table 10 shows the ultraviolet protection factors of control and treated jute fabrics. UPF ratings of jute fabrics mordanted with natural alum and stannous chloride, but not dyed are the same as that of control (bleached) jute fabric. This implies that alum and stannous chloride do not have significant UV-stability action. The jute fabrics dyed with annatto after pre-mordanting with alum or stannous chloride have improved UPF values indicating the UV-stability action of annatto upon exposure to UV light. Though the effects of both mordants on UPF values of dyed jute fabrics seem to be less significant, the transmission levels of UVA and UVB of the pre-mordanted dyed fabrics are lower than those of the unmordanted dyed fabrics. The mean UPF values of pre-mordanted dyed fabrics are also higher than that of jute fabric dyed with annatto without mordanting. The dual-mordanting

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Table 6 Effect of additive application on wash fastness of dyed fabric pre-mordanted with alum and SnCl2 Fabric type

Mordant type No mordant, no additive

Alum (10% owf)

SnCl2 (10% owf) Alum (4% owf) + SnCl2 (6% owf)

Change Staining Change Staining Change Staining Change Staining in in in in colour colour colour colour Control 1 (dyed without mordanting and without additive)

1–2

3

Control 2 (dual-mordanted with alum + SnCl2 , but without chitosan/CTAB)

2–3

3–4

2–3

3–4

2–3

3–4

0.5% chitosan

2–3

4

2–3

4

2–3

4

1% chitosan

3

4

3

4

3

4

1.5% chitosan

3

4

3

4

3

4

2% chitosan

3

4

3

4

3

4

3

3–4

3

4

3

4

3–4

4

3–4

4

3–4

4

1%

CTABa

2% CTAB a CTAB

= N-Cetyl-trimethyl ammonium bromide

on the dyed jute fabrics with these two metallic salts also does not improve the UPF rating. The findings of Chattopadhyay et al. [7] corroborated this trend of UPF rating achieved with annatto-dyed jute fabrics. The benzotriazole in the application on the dyed jute fabrics improved the UPF rating and mean UPF value. This improvement in UV protection properties is due to the UV-absorbing property of benzotriazole. This result is corroborated by the light fastness value of the jute fabric treated with benzotriazole.

3.5 Antimicrobial Activity of Jute Fabrics The antimicrobial activities of the dyed jute fabrics are shown in Table 11. The jute fabric samples inoculated with E. coli (a Gram-negative bacterium) showed a higher reduction of bacterial growth than what was observed on the fabrics inoculated with S. aureus (a Gram-positive bacterium) which has thicker cell walls imparting it with more resistance to antimicrobial chemicals than E.coli. Annatto has an antimicrobial

206

R. Chakraborty et al.

Table 7 Effect of additive application on wash fastness of dyed fabric pre-mordanted with alum and tannic acid Fabric type

Mordant type No mordant, no additive

Alum (10% o.w.f)

Tannic acid (10% Alum (5% owf) owf) + Tannic acid (5% owf)

Change Staining Change Staining Change Staining Change Staining in in in in colour colour colour colour Control 1 (dyed without mordanting and without additive)

1–2

3

Control 2 (dual-mordanted with alum + tannic acid, but without chitosan/CTAB)

2–3

3–4

3

3–4

3

3–4

0.5% chitosan

2–3

4

3

3–4

3

3–4

1% chitosan

3

4

3–4

4–5

3–4

4–5

1.5% chitosan

3

4

3–4

4–5

3–4

4–5

2% chitosan

3

4

3–4

4

3–4

4

1% CTAB*

3

3–4

3

4

3–4

4

2% CTAB

3–4

4

3–4

4–5

3–4

4–5

property as evident from the data that un-mordanted dyed fabric showed high bacterial inhibition. The application of mordants on the dyed jute fabrics augmented this antibacterial property to some extent. And finally, the treatment of chitosan gave the dyed fabrics more resistance to bacteria.

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Table 8 Effect of additive application on light fastness of dyed fabric pre-mordanted with alum and SnCl2 Fabric type

Mordant type No mordant, no additive

Alum (10% owf)

SnCl2 (10% owf)

Alum (4% owf) + SnCl2 (6% owf)

Light fastness grading Control 1 (dyed without mordanting and without additive)

2–3

Control 2 (dyed, dual-mordanted with alum + SnCl2 )

2–3

2–3

2–3

Dyed, dual-mordanted with alum + SnCl2 , treated with 1% benzotriazole

3–4

3–4

3–4

Table 9 Effect of additive application on the light fastness of dyed fabric pre-mordanted with alum and tannic acid Fabric type

Mordant type Alum (10% owf)

Tannic acid (10% owf)

Alum (5% owf) + Tannic acid (5% owf)

Light fastness grading Control 1 (dyed without mordanting and without additive)

2–3

Control 2 (dyed, mordanted with alum + TA)

2–3

3–4

3–4

Dyed, dual-mordanted with alum + TA, treated with 1% benzotriazole

3–4

4–5

4–5

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Table 10 Effect of mordants and additives on ultraviolet protection property of jute fabric Sample

UPF

UPF rating

Mean

SD

Control (scoured and bleached))

17.21

2.81

Mordanted with alum (10%)

19.25

Mordanted with SC (10%) Mordanted with TA (10%)

Transmission (%) UVA

UVB

10

10.20

7.95

3.02

10

5.89

5.91

18.02

3.35

10

6.02

5.85

20.41

3.31

10

5.41

5.72

Dyed, no mordanting

24.35

2.84

20

5.01

4.63

Dyed, pre-mordanted with alum

26.95

2.29

20

4.42

3.92

Dyed, pre-mordanted with alum + stannous chloride

28.34

3.23

20

4.84

3.75

Dyed, pre-mordanted with alum + TA

30.89

3.1

20

4.31

3.57

Dyed, pre-mordanted with alum + SnCl2 , treated with benzotriazole

32.54

4.16

25

3.81

3.12

Dyed, pre-mordanted with alum + TA, treated with benzotriazole

35.68

3.12

30

3.15

3.02

Table 11 Antimicrobial activity of jute fabrics Sample

(S. aureus) reduction (%)

(E. coli) reduction (%)

Control (bleached jute fabric)

No reduction

No reduction

Dyed, no mordanting

(80–82)

(85–87)

Dyed, pre-mordanted with alum + stannous chloride

(90–92)

(93–94)

Dyed, pre-mordanted with alum + TA

(92–94)

(94–95)

Dyed, pre-mordanted with alum + SnCl2 , treated with chitosan (1%)

(94–96)

(95–97)

Dyed, pre-mordanted with alum + TA, treated with chitosan (1%)

(97–98)

(98–99)

Dyed, pre-mordanted with alum + SnCl2 , treated with chitosan (2%)

(97–98)

(98–99)

Dyed, pre-mordanted with alum + TA, treated with chitosan (2%)

(99–100)

(99–100)

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4 Conclusion It is found that the application of mordants can improve the colour strength of jute fabrics by forming some complex with the jute cellulose/hemicelluloses and dye molecules. Alum, stannous chloride and tannic acid alone have almost similar effects on colour strength. They individually gave the highest colour strength at 10% o.w.f application on the jute fabric. However, the combined effect of alum + tannic acid showed better colour strength than the combined effect of alum + stannous chloride. The dyeing process variables of dyeing of the pre-mordanted jute fabrics were optimized and the best results were found at 30% dye concentration, 60 min dyeing time, 60 °C temperature, 11 pH, MLR 40 and 30 gL−1 salt concentration. The fastness values of the dyed jute fabrics were found poor to average. Mordants improved the rub and wash fastness by ½ to 1 grade and functional additives viz. chitosan and CTAB further improved the fastness. The jute fabric dual-mordanted with alum + tannic acid achieved higher fastness than the one dual-mordanted with alum + stannous chloride. Benzotriazole, a UV absorber improved the light fastness of dyed jute fabric by 1 grade. Alum + tannic acid dual-application improved the light fastness more than the other one.

References 1. Samanta AK, Agarwal P, Singhee D, Datta S (2009) Application of single and mixtures of red sandalwood and other natural dyes for dyeing of jute fabrics: studies on colour parameters/ colour fastness and compatibility. J Text Inst 100(7):565–587 2. Özdemir H (2017) Dyeing properties of natural dyes extracted from the junipers leaves. (J Excelba Bieb and J Oxycedrus L) J Nat Fibers 14(1):134–142 3. Samanta AK, Agarwal P, Datta S (2008) Dyeing of jute with binary mixtures of jackfruit wood and other natural dyes—study on colour performance and dye compatibility. Ind J Fibre Text Res 33(2):171–180 4. Samanta AK, Konar A, Chakraborty S (2011) Dyeing of jute fabric with tesu extract: Part 1—effects of different mordants and dyeing process variables. Ind J Fibre Text Res 36(1):63–73 5. Chakraborty R, Singh TB, Paul P, Haloi AK (2022) Colouration with natural dyes of north eastern region of India. In: Pandit P, Singha K, Maity S, Ahmed S (eds) Textiles dyes and pigments. Scrivener Publishing, Wiley 6. Savvidis G, Zarkogianni M, Karanikas E, Lazaridis N, Nikolaidis N, Tsatsaroni E (2012) Digital and conventional printing and dyeing with the natural dye annatto: optimisation and standardisation processes to meet future demands. Colour Tech. 129:55 7. Chattopadhyay SN, Pan NC, Roy AK, Saxena S, Khan A (2013) Development of natural dyed jute fabric with improved colour yield and UV protection characteristics. J Text Inst 104(8):808–818 8. Gogoi M, Gogoi A (2016) UV ray protection property and natural dye. Int J Appl Home Sci 3(3&4):159–164 9. Arkman J, Prikryl J (2008) Application of benzotriazole reactive UV-absorbers to cellulose and determining sun protection of treated fabric spectrophotometrically. J Appl Polym Sci 108:334–341 10. Jaipura L, Paul S, Rangi A (2016) Application of chitosan to impart antibacterial property to annatto dyed fabric. Asian Res 5(1):99–105

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11. Samanta AK, Singhi D (2022) Effect of application of selective UV-absorbers/antioxidants on raw and bleached jute fabrics by pad-batch-dry process for reduction of its photodegradation and photo-yellowing character. J Nat Fibers 19(15):12100–12118

Development of Woven PPE with Regenerated Fibers to Enhance the Comfort Properties of the Wearer with Antimicrobial and Liquid Barrier Nano Particle Finish J. M. Subashini and G. Ramakrishnan

Abstract The ultimate aim of personal protective wear used by the healthcare worker is to act as a layer of protection for the skin from contact with biological hazards in the form of fluid or aerosol particles. The personal protective wear is mostly made from non-woven material. The non-woven PPE offers good protection to healthcare workers but at the same time lacks comfort. Regenerated fiber nonwoven has good thermo-regulation property, thus providing good breathability to the wearer. Thus, in this project, an attempt has been made to create a woven PPE by combining bamboo fiber with inherently anti-microbial viscose fiber. The fibers are taken in five different blend ratios of 100% bamboo, 100% viscose fiber, 50:50, 65:35, and 35:65. Bamboo fiber has good anti-microbial property by its nature and the fiber is also hydroscopic, hypoallergenic, and a natural deodorizer and used in applications of medical textile, while viscose fiber provides higher comfort. The fabric is then proposed to be treated with nano fluorocarbon to enhance the liquid barrier property of the fabric and nanosoyabean particle to enhance the anti-microbial property. The fabric liquid repellence property and anti-microbial properties are tested. The fabric comfort parameters such as air permeability, moisture vapour permeability, and thermal insulation property were tested. Among all the five samples, 50:50 ratio has good comfort properties, liquid barrier property, and antimicrobial property, which are then converted into a PPE suit for healthcare workers. Keywords Reusable PPE · Bamboo fiber · Antimicrobial fiber · Nano finishing · Liquid barrier property

J. M. Subashini (B) · G. Ramakrishnan Department of Fashion Technology, Kumaraguru College of Technology, Coimbatore, Tamilnadu, India e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024 D. Gupta et al. (eds.), Functional Textiles and Clothing 2023, Springer Proceedings in Materials 42, https://doi.org/10.1007/978-981-99-9983-5_13

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1 Introduction The primary function of medical clothing is to have high protection. However, they should also correlate with a good comfort experience for the wearer. During the pandemic, medical personnel had to work longer hours treating patients. These front-line workers need high protection to prevent themselves from the transmission of biological hazards without infecting them. The PPE acts as a barrier between the patient and the medical personnel to prevent infections. Such PPE should also possess good comfort as the workers have to spend more hours in the same suit. Comfort is a very important issue when they work in a stressful situation involving heat regulation and moisture transmission between human clothing and the environment. They need proper ventilation to maintain their body at a stable temperature. The extremely insulating and low absorbent material will cause an increase in skin temperature, resulting in greater moisture accumulation [1]. The development in the field of textile technology with innovations in natural and manmade textiles aims to enhance the comfort properties and hygiene of the user in the medical field. The fiber used in medical PPE should be non-toxic, non-allergenic, able to be sterilized, and possess mechanical properties such as strength and durability. Reusable PPE is made using 100% cotton, 100% polyester, or polyester cotton blend fabric. Natural fibers like cotton, wool, silk, etc., have higher absorbency properties so that the micro-organism can be trapped within the fiber structure. If low absorbent or hygroscopic fiber is used in the construction of PPE, the liquid will wick along the fiber surface, enhancing the capillary movement of the liquid which contains the hazardous particle [2]. Bamboo fiber is an eco-friendly, biodegradable fiber with anti-fungal, anti-bacterial, hypoallergenic, and natural deodorizer properties. It is a hygroscopic fiber and has high strength comparable to conventional glass fiber. These fibers are softer than cotton and breathable [3]. In a study, an attempt has been made to develop surgical robes, face masks, and caps from bamboo fiber. Here 100% bamboo was compared with a different blend ratio of bamboo and cotton fabric. The result shows the effectiveness towards inhibiting bacterial growth is higher in 100% bamboo compared with cotton blends. It is proven that surgical wear manufactured from bamboo fibers is most effective and provides better hygiene and safety for hospital workers [4]. The anti-microbial injected viscose fiber inherently possesses anti-microbial properties which inhibit the growth of microbes (bacteria and virus) on textiles and kills them to the extent of 99%. This type of fiber is commercially produced by Birla cellulose which provides high comfort and protectively to the user [5]. The comfort characteristic of bamboo fabric is studied [6] with different blend proportions with cotton and the result concludes that the bamboo fiber mixed with cotton in equal ratio shows higher comfort than their pure forms. Anti-microbial finished textile material has a wide range of medical applications. The anti-microbial finish has become an important area of medical textile and healthcare sectors, because of potential pathogenic micro-organisms present within the environment and causes cross-infection diseases. Synthetic finishing agents such as quaternary ammonium compounds (QACs), polyhexamethylenebiguanide (PHMB),

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triclosan, n-halamines, and metals (including metal oxides and salts) have a lower adverse effect [7]. A commercial bioactive agent like chitosan shows excellent antimicrobial property on the fabric, but on the other hand, they reduce the air permeability of the fabric and imparts stiffness [8]. The application of synthetic antimicrobials has several side effects and hence the antimicrobial agent derived from biological sources could be a sustainable and permanent replacement for synthetic antimicrobial agents. The nanoparticles synthesized from plant-based have higher effectiveness as well as they are more organic which can act as a replacement for inorganic antimicrobial agents [9]. Nanoparticles synthesized from soy protein are one of the widely used plant proteins to enhance the antimicrobial activity against micro-organisms for nutraceutical and drug encapsulation [10]. Though not much proof has been shown to treat the soy particle with fabric, there is proof that shows it acts as a good anti-microbial agent. The nano-aggregated soy particle has been used in the applications of agriculture and food encapsulation application as an active anti-microbial agent [11]. Generally, a liquid-repellent finish is to be applied to the fabric without affecting the breathability of the fabric. The fabric coated with polytetrafluoroethylene (PTFF) membrane, microporous polyurethane (PU), or polyester (PES) hydrophilic membrane reduced the breathability of the material, but waterproof properties was maintained for a longer period [12]. Water-repellent finish by depositing hydrophobic substances such as fluoro-chemicals, fluoro-polymers, silicon, and waxes on the fabric surface which results in a chemical barrier against liquid penetration [13]. Fluoro-chemicals provide both repellent and release properties preventing wetting and soiling and are easy for the removal of dirt, soil, etc. They also have good fastness for washing and dry-cleaning. Fluorocarbon-based nano finishes are one of the approaches suggested [14] to achieve water and stain resistance that may mimic the lotus leaf effect. In a study [15] it is observed that the fabric finished with nano-chemicals can provide excellent functional performance without affecting the breathability of the fabric.

2 Materials and Method 2.1 Materials The bamboo fiber is purchased from Pallava Textiles, Erode, India. It is a regenerated bamboo fiber with a denier of 1.2 D and fiber length of 38 mm, made from bamboo pulp and has natural anti-bacterial and odor-proof properties. The anti-microbial viscose fiber is purchased from Birla Cellulose, Mumbai, India. This fiber possesses good anti-microbial property as it is injected with an anti-microbial agent in its fiber stage. The fiber has a denier of 1.2 D and a length of 38 mm. The nano soyabean particle of particle size 40–50 nm and the nano fluorocarbon of particle size 20–30 nm are sourced from Sigma Chemicals, India. The fabric finished with nano-chemicals

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Table 1 Blend ratio

Ratio

Blends

Sample code

100%

Bamboo

100% B

100%

Viscose

100% VIS

50:50

Bamboo: Viscose

50 B: 50 VIS

65:35

Bamboo: Viscose

65 B:35 VIS

35:65

Bamboo: Anti-microbial

35 B: 65 VIS

can provide excellent functional performance without affecting the breathability of the fabric. The fabric is proposed to be treated with nano fluorocarbon to enhance the liquid barrier property of the fabric and nano soyabean particle to enhance the anti-microbial property.

2.2 Methods 2.2.1

Development of Yarn

The purchased fiber was separated manually into small tufts and blended to the following ratios as shown in Table 1. The yarn was developed using Ring Spinning Process, where the fiber undergoes the process from carding to simplex and the rover reduces its mass through drafting, strengthening by inserting a twist and then winding as a yarn onto a bobbin. The developed yarns have a count of 40’s Ne.

2.2.2

Development of Fabric

Yarn samples were sized with Novacol, purchased from Novotransfer, Mumbai, which is a type of starch for the warp yarns using a single-end sizing machine. The sized yarn is then warped onto a beam using a single warping machine with total ends of 1760 and the width of the warping beam is 20 inches. The yarn is then woven into the fabric with the following specifications mentioned, Table 2. Then the fabric is then taken for the finishing process using the exhaustion method.

3 Fabric Finishing The exhaustion method of the fabric finishing process is used to finish the fabric with nano soyabean and nano fluorocarbon. This method is chosen for the finish since the regenerated fabric has good absorbency properties. In this method, the fabric is immersed in a bath containing the finishing agent, and the bath is maintained at a

Development of Woven PPE with Regenerated Fibers to Enhance … Table 2 Fabric specifications [16]

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Specification

Value

Yarn count

40

EPI

88

PPI

80

GSM

112

Reed count

86

Warp cover factor

13.9

Weft cover factor

12.6

Cloth cover factor

20.24

specific temperature for a specific time that allows the finishing agent to completely penetrate the fibers. The developed fabric is first finished with nano synthesis soyabean at the concentration of 15gpl in exhaustion method using a dye bath at 70 °C for all the five samples separately to enhance the anti-microbial property of the garment. The exhaustion process involves the absorption of textile auxiliaries from the dye bath due to the substantivity of the chemicals to the textile substrate. The finished sample is taken and air-dried. The dried fabric is then finished with nano-fluorocarbon at the concentration of 50gpl in the exhaustion method for all five samples separately to enhance the liquid barrier property of the garment. The finished fabric is cured at 120 °C.

4 Testing 4.1 Comfort Properties The air permeability of the finished sample is evaluated using Air-tronic (code 3240A) Permeability tester in accordance with the standard ASTM D737. Its unit is cm3 /cm2 / sec. The water vapour permeability of the finished sample is tested using a water vapour permeability tester of model M261 cup method, under the standard ASTN E 96. Here the amount of water vapour passing through the material is calculated in units of g/m2 /24 h. The thermal resistance value of the finished samples is determined using the Skin Model Preme Tester in accordance with standard ISO 11092. Its unit is m2 k/W.

4.2 FTIR Characterization FTIR (Fourier Transform Infrared Spectroscopy) is a technique used to analyze the chemical composition of a sample by measuring the absorption of infrared radiation

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at different frequencies. The resulting absorption spectrum is used to identify the functional groups and the chemical bonds present in the sample. FTIR is a nondestructive method for analyzing the chemical composition of a sample to identify unknown compounds present in the sample or characterize the properties of the known compound. In this research, FTIR characterization is made using Shimadzu (Infrared Spectrum) to identify the presence of nano soyabean particles and nano fluorocarbon in the sample after finishing.

4.3 Evaluation of Anti-microbial Property Escherichia Coli (E. coli) bacteria strains are used for testing of anti-bacterial activity of the fabric. E. coli is a common micro-organism present in hospitals. Generally, antimicrobial activity is measured in terms of the zone of inhibition. The resisted zone by finish which is not affected by the bacteria is known as the antibacterial efficiency of the finished sample. Antibacterial activity of textile materials is carried out using the Parallel streak method and test method AATCC147 (agar plate test) and the results of the test are shown.

4.4 Evaluation of Liquid Barrier Property The liquid barrier property of the fabric was measured by the surface contact angle test method. Contact angle refers to the measurement of surface free energy at the interface of a liquid and fabric surface in accordance with the standard of ASTM D 5725. It is also known as a wetting angle, which is formed when a drop of liquid is placed on the fabric surface and its contact angle is measured. The higher the angle, higher is the surface repellency.

5 Results and Discussion 5.1 Comfort Properties The comfort properties of test fabrics are reported in Table 3.

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Table 3 Comfort properties of fabric samples Samples code

Air permeability (cm3 / cm2 /sec)

Water vapour permeability (g/m2 /24 h)

Thermal resistance (m2 k/ W)

100% B

114.86

1028.95

49

100% VIS

118.93

957.98

53

50 B: 50 VIS

127.53

1109.46

52

65 B:35 VIS

120.26

959.77

68

35 B: 65VIS

121.66

912.84

70

Fig. 1 Air permeability values compared with different blend ratios

5.2 Air Permeability From Fig. 1, it is observed that the air permeability of 50:50 blend fabric has higher values even after finishing. Comparatively, the 65:35 blend and 35:65 blend have good air permeability value. Moreover, bamboo: anti-microbial viscose fabrics have higher air permeability than their pure fabrics. Bamboo fiber, as well as viscose fiber, generally has a grooved structure, which provides a large surface area that leads to lower porosity comparable to other natural fibers such as cotton and linen [17].

5.3 Water Vapour Permeability From the water vapour permeability values (Fig. 2), the 100% bamboo and 50:50 blend have a high WVP value, and the 100% anti-microbial viscose and 35:65 blend

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Fig. 2 Water vapour permeability values compared with different blend ratios

shows less WVP value. Thus, increase in the ratio of bamboo results in higher WVP of the fabric. Generally, bamboo fiber has good absorbency properties than viscose. The moisture absorption of bamboo fibers is observed more than that of cotton, lyocell, viscose rayon, modal, and soyabean [18].

5.4 Thermal Resistance The developed fabric samples are tested for thermal resistance property. From Fig. 3, the 100% bamboo, 50:50 blend, and 100% antimicrobial viscose samples show a lower value of thermal resistance with a marginal difference. Here 35:75 blend shows a higher thermal resistance value. Lower thermal resistance in a garment results in a gradual loss of heat from the skin to the outer environment under a certain set of climatic conditions, thus providing a cooler feeling to the wearer.

5.5 FTIR Analysis The FTIR spectrum of the nano soyabean and nano fluorocarbon treated sample showed several absorption bands, which represent the characteristics of the functional groups present in the sample. In the range of 3200–3500 cm−1 , a strong and broad absorption band was observed. This bond occurs with corresponds to the stretching vibration of the hydroxyl group (–OH) present in carbohydrates and proteins. Another strong absorption band was found near 1650 cm−1 which is characteristic of the

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Fig. 3 Thermal resistance values compared with different blend ratios

amide I band of proteins was observed. The absorption band in the range of 1020– 1150 cm−1 was observed, which corresponds to the stretching vibration of C–O–C band in carbohydrates. From the spectrum band range, it shows the presence of protein and carbohydrates group which clearly shows the presence of soyabean in the sample (Fig. 4). The spectrum shows a strong absorption band in the range of 1100–1300 cm−1 , which can be attributed to the presence of C–F stretching vibrations found in the sample. The absorption band in the range of 2850–3000 cm−1 was also observed,

Fig. 4 FTIR analysis of the sample finished with nano soyabean and nano fluorocarbon

220 Table 4 Zone of inhibition of E.coli in fabric samples

J. M. Subashini and G. Ramakrishnan

Sample code

Zone of inhibition (mm) E. coli

100% B

5

100% VIS

8

50:50

6

65:35

5

35:65

6

Fig. 5 Anti-microbial test results of the samples

which is a weaker absorption band indicating the presence of C–H stretching vibrations. The relative abundance of the C–F and C–H functional groups in the sample was estimated by comparing the intensity of the absorption band and the results show C–F group was more abundant than the C–H group, with a ratio of ~3:1. This shows that the sample is predominantly compound of C–F bands, which has distinct properties to enhance the stability, volatility, and hydrophobicity. The presence of C–F bond in the sample indicated that the fabric has hydrophobic properties.

5.6 Anti-microbial Property The results show that 100% anti-microbial viscose, 50:50 blend, and 35:65 blend fabric have high antimicrobial efficiency. The 100% bamboo and 65:35 blended fabric sample have very mild penetration of bacteria compared to other fabrics. Thus, the developed fabric with nanoparticle finish is found to have good antimicrobial efficiency and it is suitable for the development of PPE for healthcare workers (Table 4 and Fig. 5).

5.7 Liquid Barrier Property The contact angle for water droplet on the test fabrics is shown in Table 5.

Development of Woven PPE with Regenerated Fibers to Enhance … Table 5 Contact angle of droplets with the fabric surface

221

Samples code

Angle of contact

100% B

107o

100% VIS

105o

50:50VIS

110o

65 BAM:35 AM VIS

115o

35 BAM: 65 AM VIS

112o

From the results, it is clear that the fabric after being finished with nanofluorocarbon shows excellent liquid barrier properties. The contact angle measurement values for all five samples are above 90° which means the surface of the fabric becomes hydrophobic when the fabric is treated with nano-fluorocarbon. In general, the hydrophobic textile surface is developed by coating/ depositing low-surface energy material on its surface. This is attributed to the fact that, due to the presence of nano-fluorocarbon concentration in the finishing solution it reduces the surface energy of finished fabric which results in a higher contact angle.

5.8 Comparing the Results with Commercially Available Non-woven PPE See Table 6. Table 6 Comparison of test samples with commercial non-woven PPE Sl. no

Types of samples

GSM

1

PTFE (membrane) [19]

29.1

2

Polyethylene (Spun bonded) [19]

3

Air permeability cm3 /cm2 /sec

Water vapour permeability g/m2 /24 h

Thermal resistance m2 K/W

5.97

560

100

49

5.97

540

105

Polypropylene (SMS) [19]

60

37.43

620

100

4

100% Bamboo

112

114.86

1028.92

49

5

100% AM Viscose

113

118.93

957.98

53

6

50 Bamboo:50 AM Viscose

112

127.53

1109.46

52

7

65 Bamboo:35 AM Viscose

112

120.26

959.77

68

8

35 Bamboo:65 AM Viscose

113

121.66

912.84

70

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6 Conclusion From the above results on the development of woven PPE to enhance comfort and barrier protection it is concluded that the selection of fiber that has hygroscopic nature and natural anti-bacterial is highly preferable. To achieve more comfort with protection, the bamboo fiber and antimicrobial viscose fiber give good results. The essential function finish for a PPE such as anti-microbial and liquid barrier finish is achieved with the help of nano chemical finish compared to other conventional finishing agents. The nano soyabean particle shows excellent anti-microbial properties when treated with both blended fabrics. The liquid-repellent finish is achieved with nano-fluorocarbon compared to other manmade repellent finishing agents. From the above data, it is understood that the fabric made from a 50:50 blend of bamboo and anti-microbial viscose has shown good results in comfort property and antimicrobial properties. Though 100% bamboo fabric has good results in comfort properties, its antimicrobial activity seems lower. The 100% antimicrobial viscose fabric has less WVP value but shows good results in other properties. The 35:65 blend and 65:35 blend fabrics have comparatively lower properties than the other three samples. Compared to the comfort properties of commercially available nonwoven PPE, the woven PPE developed from bamboo and antimicrobial viscose has high comfort and also possesses good antimicrobial activity. It is a sustainable and eco-friendly wear for healthcare workers. Acknowledgements We thank the management of Kumaraguru College of Technology, Coimbatore, India, and the research center of the Department of Fashion Technology, KCT TIFAC-CORE for providing the necessary support in submitting this research paper and permitting us to process the work in their Advanced Manufacturing Laboratory.

References 1. Abreu I, Ribeiro P, Abreu MJ (2017) The issue of thermal comfort of medical clothing in the operating room. Dyna 84:234–239 2. Kilinc FS (2015) A review of isolation gowns in healthcare: fabric and gown properties. J Eng Fiber Fabr 10:155892501501000 3. Hakeem KR, Jawaid M, Rashid U (2014) Biomass and bioenergy: processing and properties. 4. Ramachandralu K (2010) Development of surgical clothing from bamboo fibres. In: Medical and healthcare textiles. Woodhead Publishing, pp 171–180 5. Brila Cellulose [Internet] (2020) [cited 2021 May 9]. www.brilacellulose.com 6. Prakash C, Ramakrishnan G, Koushik CV (2013) A study of the thermal properties of bamboo knitted fabrics. J Therm Anal Calorim 111:101–105 7. Babu KM (2003) Antimicrobial finishes for textiles. Asian Text J 12:64–68 8. Joshi M, Ali SW, Purwar R, Rajendran S (2009) Ecofriendly antimicrobial finishing of textiles using bioactive agents based on natural products. Indian J Fibre Text Res 34:295–304 9. Mondal MIH (Ed) (2021) AT from NRWP. Antimicrobial textiles from natural resources. n.d. 10. Teng Z, Luo Y, Wang Q (2012) No title nanoparticles synthesized from soy protein: preparation, characterization, and application for nutraceutical encapsulation. J Agric Food Chem 60(10):2712–2720

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11. Lee H, Yildiz G, dos Santos LC, Jiang S, Andrade JE, Engeseth NJ et al (2016) Soy protein nano-aggregates with improved functional properties prepared by sequential pH treatment and ultrasonication. Food Hydrocoll 55:200–209 12. Cloud RM, Cao W, Song G (2013) Functional finishes to improve the comfort and protection of apparel. Adv Dye Finish Tech Text 258–279 13. Hunter LA (2009) Waterproofing and breathability of fabrics and garments. Woodhead Publishing, Cambridge 14. Shishoo R (2002) Recent developments in materials for use in protective clothing. Int J Cloth Sci Technol 14:201–215 15. Krishnasamy J, Senthilkumar T, Neelakandan R (2017) Development of breathable and liquid/ microbes barrier woven surgical gowns for hospital usage. Indian J Fibre Text Res 42:453–464 16. Subashini JM, Ramakrishnan G (2022) Study on mechanical properties for the development of reusable PPE for healthcare workers. AIP Conf Proc 2446(1) 17. Basit A, Latif W, Baig SA, Afzal A (2018) The mechanical and comfort properties of sustainable blended fabrics of bamboo with cotton and regenerated fibers. Cloth Text Res J 36:267–280 18. Yuksek IO, Ozdemir O (2010) Investigation of regenerated bamboo, cotton, and bamboo/cotton blend yarn characteristics. Fiber Soc Spring 2010 Int Conf 19. Lee S, Obendorf SK (2007) Barrier effectiveness and thermal comfort of protective clothing materials. J Text Inst 98:87–98

Surface Modification Techniques in Textiles: A Review S. Periyasamy, Deepti Gupta, M. Parvathi, and Satyajeet B. Chaudhari

Abstract Surface Engineering techniques have been explored extensively in textiles for their many advantages. This paper discusses briefly the various techniques and their notable applications in textiles for the enhancement of textile properties. Lowtemperature plasma, Excimer UV lamps, and Chemical and Enzyme techniques are discussed with some experimental results and discussions. The development of various functional surfaces with physicochemical modifications is presented. Silk and polyester are specifically presented as examples of differential surface, finishing, and dyeing aspects. The suitability of surface modifications in technical textiles/ textile composite examples is presented. The use of various characterization techniques such as AFM, SEM, and Chemical Analysis is also indicated. The discussion is supported by works of literature and establishes the importance of surface modification techniques in textiles. Keywords Low-temperature plasma · VUV excimer lamp · Silk · Polyester · Surface modification

1 Introduction The surface of textiles plays a vital role in many applications both technically and aesthetically while the bulk properties contribute to the stability or durability of the structure itself. The final texture and surface-related functional properties are determined by the choice of consumers, for example, the colour, design and functional S. Periyasamy (B) · S. B. Chaudhari Faculty of Technology and Engineering, Department of Textile Engineering, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, India e-mail: [email protected] D. Gupta Department of Textile and Fibre Engineering, Indian Institute of Technology, New Delhi, India M. Parvathi Department of Textile Chemistry, SSM College of Engineering, Komarapalayam, Namakkal, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024 D. Gupta et al. (eds.), Functional Textiles and Clothing 2023, Springer Proceedings in Materials 42, https://doi.org/10.1007/978-981-99-9983-5_14

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properties like the ability to transfer and absorb moisture in addition to the feel, handle, drape, and so on. In technical textiles also, there are very specific requirements of compatibility with the choice of base fibres, chemicals and other substances as they might need engineering of structures according to certain application requirements. Therefore, the practice of developing surface properties has been there in developing the products, for example, creating particular print patterns and designs could be regarded as surface development aspects. In this connection, a threshold definition to differentiate bulk and surface needs to be stated. In general, it may be stated that the surface would essentially form a very low percentage composition of the total material, for example, it may be broadly stated to about one per cent of the total and the rest being the bulk. Accordingly, if the fibre diameter is assumed to be 10 μm, then the surface may be limited to about 0.1 μm. So any changes applied, if restricted around 0.1 μm of the fibre surface, may be regarded as a surface modification. The deciding factor between the surface and bulk is that when done something to an object within the surface level, it would not alter the bulk properties at least notably. In this context, it cannot be denied that the practice of surface treatments would be inseparable from time immemorial though such specific scientific discussions may have evolved only in the last century. Surface modification can be enacted either through chemical, physical, or physicochemical processes. Conventionally, chemical processes like printing, finishing, painting and other treatments have been there but with modernization, use of chemicals has been a concern for society. So, the alternative techniques of surface modifications using physical or physicochemical techniques have been explored and are listed below. • • • • • • •

Corona Discharge Flame Treatment Gaseous Plasmas UV Irradiation Electron Beam Bombardment γ-Ray Treatment Ion Beam Bombardment.

Out of these techniques, plasma techniques have been gentle and versatile in the surface modification process, particularly for textiles. Plasma is the 4th state of matter in addition to air, water and solid. Plasma is an ionized gas and is highly reactive as it contains highly reactive species such as +ve, −ve charges, radicals, electrons, excited molecules and atoms (Fig. 1). Some of the common examples of plasma found in nature are sun, lightning bolt and simple everyday flames as seen in Fig. 1. Obviously, the use of such highly reactive sources to treat the surface of textiles is complicated. Hence, at this point the classification of plasma as hot and cold plasma need to be presented. The temperature of hot plasma remains at a very high range (beyond 500 ºC) while the low-temperature plasma essentially has its range around room temperature. Such temperature difference between hot and cold plasma is explained through thermal equilibrium between neutral particles and the charged particles which do exist in hot plasma and are

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(a)

(b) Fig. 1 Plasma a Reactive environment, b Common examples

missing in cold plasma. The absence of thermal equilibrium makes the heavy particles remain at a low temperature and lighter particles assume higher kinetics making them participate in the reactions restricted to the surface. Thus, the low-temperature plasma is formed and suited for surface treatments without affecting the bulk properties. Historically, the first trials of plasma on textiles are traced back to the early 1960s. Processes in the 1960s had 109 excited particles/cc compared to 1012/cc in the 1990s making more energy available to modify surfaces and so its research and developments have been augmented. Some of the generally explored areas of surface modification techniques in textiles and general physical process and substrate interaction are summarized in Table 1.

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Table 1 Application and effect of plasma in textiles Generally explored areas in textiles

General physical process and substrate interaction

• Modification of hydrophilicity// hydrophobicity adhesion – Composite applications • Sterilization/antimicrobial properties • Change of surface morphology – Shade Depth – Rate of dyeing – Modifying friction properties • Altering dyeability, printability • Desizing, spin finish removal • Soil release properties • Fastness properties • Shrink proofing of wool • Dye uptake, etc.

• Physical phenomena in plasma-assisted surface modifications – Etching/re-deposition – Effect of plasma parameters on etching – Surface morphology and roughness – Chain scission • Chemical phenomena in plasma-assisted surface modifications – Radical formation – Grafting – Polymerization – Cross-linking – Surface functionalization

Over the past decades there have been many research works in the areas of surface modification of polymers and textiles. In the literature, many experimental works and reviews can be found related to the above-mentioned areas of applications (Table 1), [1–4]. However, in this article, it is of interest to present some of the findings of our research team over the past years which include low-temperature plasma treatment, excimer lamp irradiation and also the chemical treatment of silk, polyester and nylon textiles.

2 Low-Temperature Plasma (LTP) Treatment of Polyester (PET) Polyester fabric with the specification of EPI-114, PPI-82, warp count 72 Tex, weft count 90 Tex and cover factor of 147 was subjected to dielectric barrier discharge (DBD) type of atmospheric pressure plasma treatment and the study was carried out for various timings and its effect on hydrophilic characteristics such as wetting and wicking was studied [5]. The change in hydrophilic properties of the polyester fabric is shown in Fig. 2. It can be seen that the wetting and wicking time decreases with increase un duration of the plasma treatment. In a more general perspective, such decreasing trend appears to the drastic in the beginning and gets stabilized over time. This was attributed to the formation of oxygen containing groups such as carboxyl, hydroxyl and also carbonyl groups. In addition to the formation of functional groups, increase in surface roughness (micro and nanopores) contributes to the spreading and wicking of water [5, 6].

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Fig. 2 Effect of DBD-LTP treatment on hydrophilic characteristics of polyester, a Wetting time, b Wicking time

(a)

(b)

3 Irradiation of Microdenier Polyester (PET) Using VUV Excimer Though the low temperature plasma (LTP) treatments have proven to be a promising method for surface modification of textiles, it has a few challenges such as operating at atmospheric pressure with a uniform glow discharge. Hence, as a novel technique, the excimer lamp has been explored which operates at the monochromatic wavelength at the VUV range of 172 nm. Treatment of micro denier polyester with the excimer lamp was done to enhance the shade depth which is one of the serious problems in the dyeing of micro denier polyester fabrics [6]. Micro denier polyester fabric having 85 GSM was first subjected to VUV excimer irradiation for various timings followed by acrylic acid grafting and basic dyeing. The results of dyeing in terms of shade depth are presented in the Fig. 3. It can be observed from Fig. 3 that the shade depth of the micro denier polyester sample increased with the increase in irradiation timing which might be because of the large quantity of grafting on the surface of the polyester sample. Such high grafting would be a result of a high degree of surface functionalization due to irradiation effects [6].

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Fig. 3 Effect of VUV excimer lamp irradiation on shade of microdenier polyester

4 VUV Excimer Irradiation of Silk In another set of studies, silk fabric samples were taken for surface modification. The basic reason was silk has much of surface hydrophobicity though it is hydrophilic fibre at the overall bulk level. This is because of the amino acid composition of silk. Hence, silk fabric is not spontaneous in moisture absorption and transmission. Therefore, the surface modification of silk was found essential. It was found that the irradiation increases its wetting and wicking characteristics similar to the polyester sample as shown in Fig. 2 [5]. Such irradiation of silk also resulted in nanoscale surface roughening and the pores were carefully measured through high resolution scanning electron microscope whose values can be seen in Table 2. Such pore formation can be attributed to the strong etching effect of high energy VUV irradiation at 172 nm [5]. The detailed description of the mechanism is presented in our earlier work [5]. In the same paper it has been reported that such irradiation of silk does not affect the bulk properties of silk fibre [5]. In the extended study, the sensitivity of the irradiation has been reported in detail as an effect of one side surface modification of silk fabric with VUV excimer irradiation [3]. In the work, it has been established that the wetting of the surface is much faster on the irradiated side while it is slower on the opposite side. The effect of irradiation has been well established by the atomic force microscope analysis as shown in Fig. 4. The presence of nano roughness can be seen on the irradiated surface while not on the other side [7]. Table 2 Nanopore formation on silk fibre due to VUV excimer irradiation

VUV irradiation (s)

Pore size (nm)

60

92

180

103

300

124

900

187

Surface Modification Techniques in Textiles: A Review

(a)

231

(b)

Fig. 4 Atomic force micrograph of silk fibre, a Non-irradiated surface b Irradiated surface

In another study, the excimer lamp irradiation technique has been used to develop a stain repellent dual characteristics silk fabric with the outer repellent effect and inside absorption characteristics which was done by first treating silk with fluorocarbon followed by VUV irradiation on the inner side [8]. It has been found that the irradiation technique could be used for the development of dual surfaced silk fabric with inside hydrophilic and outside hydrophobic character [9]. Further, the analysis of chemical changes was carried out using carbonyl group analysis technique along with exploring the lamp geometry and the treatment sensitivity as seen in Fig. 5 [10]. Figure 5 shows the sensitivity of the VUV irradiation as an effect of lamp circular geometry in terms of absorbance value of carbonyl group analysis. It can be seen that the closest point of the fabric has high absorbance while the farthest point has low value which discloses the sensitivity of the treatment.

Fig. 5 Carbonyl group estimation and effect of lamp geometry

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5 Conclusions Surface modification of textiles using physicochemical processes has been discussed in this paper. Low temperature plasma (LTP) treatment of polyester fabric resulted in decrease in wetting time from 80 to 5 s for plasma treatment of 0–90 s and decrease in wicking time from 233 to 74 s for plasma treatment of 0–240 s. Beyond these treatment timings, such effects are found to be stabilized. VUV Excimer lamp irradiation followed by acrylic acid grafting of micro denier polyester has shown improved K/S value for basic dyeing. Further VUV irradiation of silk showed the formation of nanopores with the average size of 92 nm and 187 nm for the irradiation timings of 60–900 s with the increasing trend for the intermediate irradiation timings. Formation of hydrophilic groups by the VUV irradiation has been proven by the carbonyl group analysis using UV absorbance value of 0.37 at the lamp center point (the closest point to the lamp surface) and 0.08 at the farthest point away from the lamp center, and hence yielding the effect of lamp geometry. AFM micrograph depicted the formation of nanopores and the irradiation effect being restricted only to one side while the other unexposed side being unaffected.

References 1. Maryam N, Abu NMAH, Aminoddin H (2022) Plasma-assisted antimicrobial finishing of textiles: a review. Engineering 12:145–163 2. Ana DK, Bratislav MO, Sonja S, Antje P, Milorad MK, Mirjana MK (2022) Enhanced antimicrobial activity of atmospheric pressure plasma treated and aged cotton fibers. J Nat Fibers 19(14):7391–7405 3. Chang L, Chang EZ, Xuehong R, Wenjun T, Changhai X, Chi-Wai K, Qing Z, Huixia L, Zhonglin X (2022) Plasma deposition for antimicrobial finishing of cellulosic textiles. The J Text Inst 113(11):2515–2522 4. Aminoddin H, Maryam N (2020) Cleaner dyeing of textiles using plasma treatment and natural dyes: a review. J Clean Prod 265:121866 5. Periyasamy S, Gupta D, Gulrajani ML (2007) Nanoscale surface roughening of mulberry silk by monochromatic VUV excimer lamp. J Appl Polym Sci 103(6):4102–4106 6. Gupta D, Siddhan P, Banerjee A (2007) Basic dyeable polyester: a new approach using a VUV excimer lamp. Color Technol 123(4):248–251 7. Periyasamy S, Gupta D, Gulrajani ML (2007) Modification of one side of mulberry silk fabric by monochromatic VUV excimer lamp. Eur Polym J 43(10):4573–4581 8. Periyasamy S, Gulrajani ML, Gupta D (2007) Preparation of a multifunctional mulberry silk fabric having hydrophobic and hydrophilic surfaces using VUV excimer lamp. Surf Coat Technol 201(16–17):7286–7291 9. Periyasamy S, Gulrajani ML, Gupta D, Parvathi M (2015) Surface analysis of VUV irradiated mulberry silk through carbonyl group estimation. Fibers Polym 16(2):420–427 10. Periyasamy S, Krishna Prasad G, Raja ASM, Patil PG (2018) Submicron surface roughening of aliphatic polyamide 6,6 fabric through low temperature plasma and its effect on interfacial bonding in rubber composite. J Indus Text 47(8):2029–2049

Sustainable Fibres and Products

Development of Nettle Fibre Blended Apparel Textiles Kartick K. Samanta, A. N. Roy, H. Baite, S. Debnath, L. Ammayappan, L. K. Nayak, A. Singha, and T. Kundu

Abstract Nettle plant is not properly cultivated for fibre production, rather it is naturally grown as a forest weed without much established economic value-chain. The plant grows as a wild in Africa and several Asian countries. It is prominently grown in the Himalayan region, thus popularly known as Himalayan nettle. In India, nettle is available in Uttarakhand, Manipur, Himachal Pradesh, Sikkim, Arunachal Pradesh, and West Bengal. After cutting the stem, the bark is removed/ peeled, and the fibre is extracted following the suitable retting process of ribbon or whole plant stem. The present chapter summarizes the studies on fibre extraction and evaluation of fibre’s optical, physical, chemical, and morphological properties. Fibre is mostly used in making ropes, twine, and fabric from the hand spun yarns. For conversion of nettle fibre into yarn, a similar processing line, used for flax and hemp fibres processing, might be considered. Suitable chemical treatment could enhance the properties of fibres for developing fashionable apparel, handicrafts products, home and technical textiles, and composite through blending/ mixing with other natural or synthetic fibres. Nettle fibre due to its structure exhibits good oil sorption characteristics. In one study, the nettle fibre was blended with regenerated rayon (RR) fibre in blend ratios of nettle/RR: 100/0 and 50/50 using long-draft fibre spinning system (used in jute processing). Pure or blended yarn was used in the weft direction to produce union fabrics, keeping the 2/60 s cotton yarn as warp. Apparel wears were developed from pure and blended nettle fabrics. Keywords Nettle · Fibre properties · Blended yarn · Fabric · Apparel product

K. K. Samanta (B) · A. N. Roy (B) · H. Baite · S. Debnath · L. Ammayappan · L. K. Nayak · A. Singha · T. Kundu ICAR-National Institute of Natural Fibre Engineering and Technology, 12 Regent Park, Kolkata, West Bengal 700040, India e-mail: [email protected] A. N. Roy e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024 D. Gupta et al. (eds.), Functional Textiles and Clothing 2023, Springer Proceedings in Materials 42, https://doi.org/10.1007/978-981-99-9983-5_15

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1 Introduction Natural fibres like cotton, silk, wool, flax, ramie and jute, and man-made fibres like viscose, cellulose acetate, polyester, acrylic and nylon are used for the production of different textile products [7, 9, 23, 25–27, 35]. Both the natural as well as synthetic fibres fulfil the requirement of textile industry for the production of apparel, home and technical textiles. Synthetic (manmade) fibres fulfil the major quantum of fibre demand for fabric and other industrial applications, due to their key merits like ease of production in large quantum, uniformity, tailor-made fibre-structure, appropriate cost, and adequate mechanical properties. On the other hand, the well explored natural fibres like cotton, silk, wool, jute, flax, ramie, etc., could not fulfil the total requirement of natural fibre for textile and other industrial applications. Thus, the research is directed to explore other plant- and animal-based natural fibres. In this line, textile grade fibre has been extracted from the plant leaf/ stem/ fruit cover like Okra, Banana, Pineapple, Coconut, Cornhusk and Areca nut husk along with their detail fibre characterization and suitable end applications [6, 12, 15, 19, 26, 33]. In this context, nettle fibre, an important plant resource mostly naturally grown in the high altitude of Himalayan region as wild, is now getting notable attention for textile end applications [28, 29]. Nettle is a common herbaceous plant that consists of around 30–45 species. The fibre is part of the Urticaceae family like ramie (Asian nettle, Boehmeria nivea) and belongs to the genus Urtica. In Europe, the Urtica Dioica, i.e., stinging nettle is the most important species. The fibre has a long history of making hand spun yarn since early 77 BC and finally to make twines from the yarns using a fly wheel [8]. Himalayan nettle (Girardinia diversifolia) is a perennial plant grown in the temperate and sub-tropical area with height ranging from 0.6 to 2 m [28]. It is a potential fibre yielding plant, which grows mostly in a moist and shady habitat in the waste lands and forest areas of India, China, and Malaysia. All parts of the plants are covered with thorn like stinging hairs, which upon contact cause painful rashes. Plant grown on rich soils could yield fibre in the range 335–411 kg/ha in the second year and from 743 to 1016 kg/ha in the third year [8]. Nettle plants have been used for centuries as a fibre resource and extensively in Europe till sixteenth century for making clothes. However, it lost its popularity after cotton was slowly introduced in the market, owing to its advantages in harvesting and spinning [28]. Date back to the Bronze age, in Denmark, burial shrouds made of nettle fabrics have been revealed. Thomas Campbell reported the use of nettle fibre in Scotland in 1835 [8]. Nettle fibre was used in the Great Britain up to about 1860 for making a strong and durable cloth. With the advancement of other plant fibre, it was slowly discontinued. During the first and second world wars, nettle was used as a substitute to cotton, as the German felt shortage of cotton for their soldiers’ uniforms. Nettle plant was also used for extraction of green dye for camouflage during the second world war. In India, nettle plant is mainly found in the foothills of Himalayas, in the state of Uttarakhand, Jammu and Kashmir, Himachal Pradesh, Sikkim, Arunachala Pradesh, and West Bengal. Like jute, flax, ramie and hemp, the fibre comes from the stem of the plant and is found to be very long and strong. They are categorized as

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‘bast fibre’. After cutting the stem, fibre could be extracted by retting of either whole plant or retting of extracted ribbon. Being a potential natural fibre suitable for winter and summer wear, the nettle fibre holds interest among the lifestyle and sportswear manufacturers in the textile value chain. Around 15,000 tonnes of raw nettle fibre have been reported available by the Uttarakhand Bamboo and Fibre Development Board (UBFDB) having different potential applications [8]. Plant stems as well as the fibre of nettle are used to prepare various traditional handicrafts in several Balkan countries. Nettle fibre material in Bulgaria, locally known as Kopriva, is used for sustainable manufacturing of cloth, sack, cord, and net. In Romania, nettle is known as ‘Urzica’, which is used as a substitute of cotton for fishing net and paper making. In Serbia, it is popularly known as ‘Kopriva’, where nettle fibre is considered as one of the major textile fibres [8]. Overall, there are wide ranges of possible handicraft and fashion items viz., doormat, flower-vase, wallhangings, door-chain, carpet, handbags, tablemat, beach umbrella, lampshade, etc., can be made from either pure nettle fibre, yarn, or fabric or in appropriate combination of those with other natural or synthetic fibres. The Himalayan nettle fibres are longer, stronger, and more elastic than flax fibres. Fibre is obtained from the stem and is useful in making ropes, twine, and fabric with hand spun yarns. Production of nettle fibre requires lots of individual operations viz., harvesting, retting, extraction, washing, and drying. The extracted fibre holds the requisite properties like fineness, strength, and pliability for making apparel, home, and industrial textiles. However, there is no appropriate standardized and modern processing technology for largescale processing of nettle fibre. Furthermore, due to difficulties in plant harvesting, appropriate retting protocol for fibre extraction, and notable variation in fibre fineness, there is a scope for further research and product development from this potential fibre.

2 Nettle Plant, Retting and Fibre Extraction Fibre extracted from bark of the stem was considered in developing textiles, as documented even in the bronze age. Attempt was also directed to produce paper from the fibre. Several benefits of use stinging nettle have also reported since ancient times. Due to the several benefits of different parts of the plant, it has been used as food. The green leaves of the plant are consumed as cooked food, in the form of tea, soup, or other beverages. This is because the leaves are rich in carotenoids, vitamins, different minerals, and also important fatty and amino acids. Penetration of fine tiny needle-like hairs into the skin, in contact with plant leaves as well as stem may lead to skin irritation. The extract from the plant is used for prevention of many inflammatory and other similar syndromes like asthma, bleeding problems, and diabetes.

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2.1 Harvesting Nettle plants are considered as ready to harvest fibre, when the plants are tall, seeds are forming and the new growth begins to come up from the root zone, and when the leaves begin to wilt and turn into yellow. The plant is cut near the ground by wearing gloves leaving around 4–6 inches from the root end.

2.2 Retting of Plant Retting, an essentially biochemical and the only process through which biopolymers such as pectin, hemicelluloses, etc., of the plant stem decompose by the action of microorganisms, releasing the fibre from the stem. It is a process, where the green plant biomass is subjected to the action of micro-organisms (bacteria and enzymes) to rot away most of the woody cellular tissues and pectineus material present around the fibre bundles. Different retting process is mentioned below. Water retting: Water retting is carried out by immersing the nettle stems in pools or tanks of water, and leaving until the bacteria have rotted the stems sufficiently to allow easy removal of fibre bundles. This method is commonly and widely practised for bast fibre like jute, but not well acceptable, as it pollutes a large volume of water. Dew retting: Nettle stems are left out in the field/ ground after harvesting. The thorough action of moisture and fungi causes the breakdown of pectineous matter of the stem. Turning of the stems periodically is required for uniform or even retting. It is being a weather-dependent process so somewhat unreliable. Dew retting is popularly practised for flax fibre. Chemical retting: In this process, nettle stalks are placed in requisite chemical solutions (alkali treatment). After extraction pre-treatment (bio-scouring) of fibre is required to remove the impurities present in the fibre and bio-softening is done to reduce the flexural rigidity of the fibre. However, the process tends to damage the fibres and also leads to environmental pollution. Fibre colour and physical properties depend on the type of retting process adopted to extract the fibre. For example, when the retting is carried out with sodium hydroxide, it shows more whiteness index than the tank water retting or retting with lower percentage of NaOH solution [2]. Microbial retting: Microbiological retting utilizes a complex microbial community or microbiome, which includes hydrolytic, cellulytic, fermenting, homo-acetogenic, syntrophic, and acetate-utilizing bacteria necessary for dissolution and decomposition of the biopolymers [1]. Retting is one of the most important factors responsible for determining the quality and yields of fibre, which depends on the type of bast fibre plant, age of the plant, temperature and pH of retting water, type and depth of water and activators, and the water quality along with microorganisms used in the process [1, 14]. Despite being many utilizations and potentiality in the export

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Fig. 1 Extraction of nettle fibre from the stem by microbial retting process

markets, little work has been carried out on nettle fibre extraction process through microbial retting. Gahlot et al. have done work on different retting of nettle plants [10]. In another study, the nettle plant stem received from Manipur, India was used for microbial retting using pectinolytic bacteria [29]. The process of extraction of fibre from the stem is depicted in Fig. 1, which leads to 1.25% dry fibre yield, calculated based on the weight of the green stem. The extraction methods either conventional retting or microbial assisted retting influence the fibre properties, in which the combination of decortication followed by water retting perhaps can provide the optimum properties [20].

3 Fibre Properties Fibre length of 43–58 mm for nettle fibre (Urtica dioica L.) with a 19–47 µ fibre diameter and 24–60 cN/tex tensile strength along with elongation at break in the range of 2.3–2.6% is apposite for application in apparel, home and/or technical textiles [2]. Furthermore, the nettle fibre shows an average value of 87 GPa Young’s modulus and ultimate stress of 1594 MPa. The fibres bundle present on outer surface of the stem are finer and longer. The fibre holds a great importance for its application in fibrebased-composite owing to its low specific weight along with high ultimate stress properties [8, 34]. When the fibre chemical composition is considered, it possesses

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Table 1 Nettle fibre properties in comparison to other bast fibres [3, 6, 18] Fibre

Tensile strength (MPa)

Elongation at break (%)

Density (g/cm3 )

Average diameter (µm)

Nettle

650

1.7

NA

20.0

Flax

343–2000

1.2–1.3

1.53

23.0

Hemp

270–900

1–3.5

1.07

31.2

Ramie

400–1000

1.2–4.0

1.56

50.0

Banana

500

1.8–3.5

1.35

160–180

Jute

320–800

1.0–1.8

1.45–1.52

110

cellulose and hemicellulose of 85%, lignin of 2.12%, ash of 2.68%, ~5% watersoluble matter, wax of 2.16%, and about other materials of 3% [36]. Some of the important properties of nettle fibre in comparison with other plant fibres are reported in Table 1 [5, 6, 8, 37]. Single nettle fibres’ tensile properties were measured by fixing them on a slotted paper holder with 10 mm gauge length for tensile stress, strain at failure and Young’s modulus of 90 fibre samples. It was found that Young’s modulus of the sample was 87 Pa and tensile strain at break of 2.11%. Tensile properties of stringing nettle fibres were also analysed along with study on fibre cross-sectional morphology by SEM [5]. As observed, the bundles of fibre are present in the inner cortex layer. Like other plant fibre, the internal hollow channel at the centre of the fibre, called lumen, is also visible and the fibre diameter was measured to be an average of 19.9 µ (±4.4) [8]. Nettle deproteinated biomass (NDB) represents 52.4% (w/w) of the dry nettle biomass and contains 695.5 g/kg non-starch polysaccharides (NSP).

4 Fibre Modification for Other Technical Applications In addition to nettle fibre inherent properties, several efforts were also directed to alter the fibre’s physical as well as tensile properties. In this direction, nettle fibre was treated with different concentration of sodium hydroxide (NaOH) viz., 0.5% and 10% NaOH solutions for different time and temperature viz., for 30 min at 30 °C (0.5%) and for 6 h at 100 °C (10% NaOH) [17, 28]. Such chemical treatments could improve the several properties of the treated fibres. It was found that tensile strength changed from 4.10 g/den in an untreated fibre to 5.57 g/den and 3.54 g/ den in the 0.5% and 10% NaOH-treated fibres. Likewise, the tensile strain value changed from 2.6% in the untreated sample to 3.6% and 2.81% in the 0.5% and 10% NaOH-treated samples, respectively. On the other hand, initial modulus was found to be reduced notably (from 184 g/den to 146 g/den) in the 10% NaOH-treated samples. Fibre fineness was measured in terms of fibre mass per weight (denier) and diameter (in micron), which shows the value of 24.6 denier and 52 µm; Both these properties get reduced to 24 denier and 20.1 denier, and 50 µ and 38 µ in

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(a)

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(b)

Fig. 2 a Optical microscopic image and b Load-extension curve of nettle fibre

the above two alkali-treated samples, respectively. As far as its structural properties are concerned, nettle fibre has 67% crystallinity index in the unmodified sample, which marginally improved to 68.6% (0.5% NaOH) and 68.4% (10% NaOH) in the treated fibres [17]. Fibre strength of 33.5 g/tex, length of 10–90 mm, and elongation of 2.7 mm were measured in other reports [22]. Optical microscopic image and the load-extension curve of nettle fibre are shown in Figs. 2a and b, respectively. Fibre shows the following physical and mechanical properties, maximum breaking load of 0.81 N, extension of 0.53 mm, total energy to break 0.23 mJ and initial modulus of 1823 cN/tex. From the optical microscopic image the fibre diameter was evaluated, which ranges from 50 to 112 µ, considering the variation within the fibre, age of the plant and fibre-to-fibre. Fibre is light yellow in colour, which is also similar colour of silk fibre. Nettle fibres due to the higher cellulose contents with desirable tenacity, can be potentially used to manufacture and reinforce the polymeric matrices. Interphase bonding between the reinforcing material and matrix can be enhanced by a suitable chemical treatment like alkali treatment that ultimately improves the composite’s flexural and tensile properties. Nettle fibre-based bio-composites can match the desirable property of an automobile product [20]. Bio-composite has been prepared from alkali-treated nettle reinforced with the epoxy resin and investigated the tensile properties like flexural strength, tensile strength, and impact strength [21]. Furthermore, drilling resistance by varying the feed rate in the range of 0.125–1.2 mm/min, spindle speed in the range of 50–800 rev/min, and drill diameter of 4–8 mm was also evaluated. It is inferred that the alkali-treated nettle fibre composite shows the impact strength of 9.2 J, flexural strength of 22 MPa, and maximum tensile strength of 30 MPa, and comparison with untreated nettle-based bio-composite, possibly due to better cleanliness of fibre surfaces than that of untreated fibres. It is also observed that drill diameter as well as feed rate both enhance the delamination of bio-composite. Green composites were also developed from the nettle fibre, as a biodegradable reinforcement along with poly (lactic acid) as a biodegradable matrix by employing

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the carding followed by compression-molding processes. Thermal stability of the composites improved, when fibre content was increased. The same is also visible from the low damping factor & loss modulus, high storage modulus, and excellent biodegradability [17]. The same authors group also mentioned that composite mechanical properties are greatly altered with the fibre orientation [16].

5 Development Nettle Yarn, Fabric, and Apparel Products Nettle fibre has a sufficient length in the range of 30–150 mm (average 62 mm) with a diameter of 77–144 mm (average 94 mm) suitable for spinning and developing yarns as well as fabric [32]. Fibre exhibits different properties in terms of fineness (15.2 den), tenacity (4.6 g/den), elongation (2.51%) and breaking force (64.9 g) for tank water retted sample. These properties depend on the type of retting process used to extract the fibre. In this direction, whiteness index of the fibre sample was lower for the tank retted sample. Cotton/nettle union fabrics, developed with different weave designs, are found to be much cheaper compared to pure nettle fabric. Fabric developed with higher thickness shows good potential for manufacturing different value-added textile products [11]. Traditionally, after extraction of nettle fibre, the dried fibre is rubbed in mud called ‘kamedu mitti’ for easy separation in manual spinning operation. Then the fibre/yarn is converted into various traditional products like scarves and shawls using a conventional loom. In order to evaluate the efficacy of performance of nettle fibre in woollen and cotton spinning systems, various fibre properties were evaluated in Uster high volume instrument and Uster-microfibre dust and trash analyser like relative fibre diameter, length and strength. It is observed that among the two spinning systems, fibre may be considered for processing in woollen spinning system satisfactory for blended upholstery fabric development (wool/nettle: 80/20) [8, 13]. On the other hand, as far as processing of nettle fibre in cotton spinning is concerned, significant fibre length variation along with nonconsistency in uniformity limits its processing in cotton system. The quality of yarn produced from the nettle fibre of wild variety is not available in a regular quality, as it is produced using the traditional manual method of spinning. Blending of nettle fibre with other natural or synthetic fibre is necessary to develop better quality yarn and fabric. Yarn developed from the 100% nettle fibre was found to be not satisfactory, as far as its yarn quality is concerned [5]. Attempt has also been made to develop nettle yarns using open-end-friction-spinning for its application in fashionable upholstery [31]. In this process, nettle fibre was mixed with short flax and polyester fibres for their usage as a wrapper fibre or core yarn, respectively. The effects of core yarn percentage, friction roller speed and spinning speed on the developed yarn properties were optimized using statistical orthogonal test method [8]. Nettle fibre was also blended with organic cotton and bamboo fibres so as to make yarn in different combinations, out of which the 50:50 blended yarn showed satisfactory results [22]. Blended yarns with count of 10 s thus developed were compared with a yarn of similar count, which was made either from wholly organic cotton or bamboo

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fibre. The blended yarns show an elongation length of 17 mm and 31 mm in case of nettle-cotton and nettle-bamboo blend yarns, respectively. Extracted nettle fibre has been used to produce a fine yarn of 60 tex or even less in a modified cotton system for developing high value clothing. The Himalayan nettle fibre has a fineness of 1.44 tex, extension of 1.5%, tenacity of 43.4 cN/tex and with specific work of rupture of 4.58 N/tex, respectively. Difficulty in spinning of yarn count less than 80 tex was noticed to make yarns from 100% nettle fibre but blending with fine viscose fibre up to 120 tex yarn was possible to spun [30]. Choudhary et al. (2013) mentioned at the primary level, the sector involved in nettle processing with a high involvement of women for harvest of plant and fibre extraction, followed by thread making. These threads produced in the traditional process were utilized to make shawls, scarves, and other cloths. People acceptance of such developed nettle products has been low till date due to roughness of the fabrics and the limited collection of colours. Such limitations have been addressed by the introduction of special spinning process to produce wholly nettle or nettlecotton fibre blended yarn with the involvement of process like straightening, cutting, 1st crushing, washing, conditioning (degumming), 2nd crushing, pre-carding and softening. After such technological alternation in the spinning, the yarn productivity as well as quality were improved [8]. Blending of nettle fibre with other natural fibres in different proportions has high potential for developing nettle-based home textiles, apparel textile, handicrafts products, composite, so on [29]. It is reported that an Italian fashion company has produced nettle fibre-based fabric for making uniforms of soldiers during first and second world wars. Products like towel were also developed from wholly nettle along with evaluation of detail sample properties [24]. Apparel fabric can be produced either from fully nettle or in blending with viscose, wool, cotton, and flax fibre. It is reported that the production of nettle-acrylic blended woven fabric [4]. In their experiment, acrylic/nettle fibres blended yarns with blend ratios of 50:50, 70:30, and 30:70 were developed for making blended textile for application in fashion wear. In their study, it was experienced that pure nettle yarns with counts of 24 s Ne and 16 s Ne were not possible to produce satisfactorily. This is because of poor pliability and higher stiffness of the fibre. Developed yarn with blend ratio of acrylic-nettle (30:70) leads to higher spinning breakages, whereas in case of other blended yarns were found to be suitable in terms of tensile strength, yarn imperfections, and hairiness. Fabrics were developed in that study, keeping either pure organic cotton or bamboo yarn in the warp direction and the blended yarns in the weft direction; the fabric properties were compared with wholly organic cotton or bamboo fabric (both in weft and warp directions). The produced textiles may be used, where the fabric aesthetic value is an important parameter [22]. Similar to other natural fibres, except cotton, nettle possesses light yellow in colour that is required to be bleached prior to dyeing/ printing [8]. Hydrogen peroxide bleaching is a widely adopted bleaching agent for cellulosic to lignocellulosic plant fibres so as to remove/depigment any natural colour compound in the fibre. Nettle fibre after bleaching exhibits better dye uptake along with satisfactory levelness in the dyeing process. Sometimes, two-stage bleaching of nettle fibre using sodium hypochlorite followed by hydrogen peroxide (H2 O2 ) is

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recommended, as the natural pigments present in nettle fibre are too deep to remove completely by hydrogen peroxide process. Two stages sequential bleaching process is preferred, when the fibre is required to be dyed in light shades. Nettle also being a lignocellulosic plant fibre may be coloured with other dye classes viz., direct, reactive, and vat. In our study, nettle fibre was procured for blending with regenerated rayon (RR) fibre in blend ratio of 50/50, as shown in Fig. 3 and the properties were compared to 100% nettle yarn. The average length of nettle fibre was approximately 40 cm and staple length of regenerated rayon (RR) was 10.8 cm. The tenacity of nettle and RR fibres were 16 cN/tex and 28.3 cN/tex, respectively [29]. Pure and blended yarns of nominal count 86 tex (2.5 lb/spindle) were developed, keeping the nominal twist per meter of 290. It is seen that tensile strain improved a little due to the introduction of RR fibre, however tenacity of the blended yarn reduced to 7.8 cN/ tex from 10.9 cN/tex for the 100% nettle yarn. It was also observed that the specific work of rupture was higher at 1.19 mJ/tex-M for the pure nettle yarn. The developed yarns were suitable for producing woven fabric in handloom, keeping those in the weft direction. With the introduction of much whiter regenerated rayon (RR) fibre in nettle/RR blended yarns, the whiteness index value increased from 50 to 60.3. It also leads to improvement in the reflectance value of light from 16.9 to 26.8 in the 100% nettle to 50/50 nettle/RR fibres blended yarns, respectively. Mechanical properties of the fabrics were measured in Instron tensile tester, Model 5567 following the ASTM D1682–1975 standard, keeping the sample width of 2.54 cm and gauge length of 7.5 cm. Speed of testing was adjusted to ensure time-to-break of a sample of 20 ± 3 s. From Fig. 4, it is seen that the maximum load carrying capacity of the developed fabric reduced a little with the introduction of RR fibre. A similar result was also seen for the initial modulus of the woven

Fig. 3 Process of making nettle/regenerated rayon (RR) fibres blended apparel textiles

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Fig. 4 Mechanical properties of blended nettle fabrics (in weft direction) [29]

fabric. However, total energy to break the fabric sample is marginally higher in the case of 50/50 nettle/RR blended fabric. Initial modulus in the blended fabric was lower, possibly due to use of much softer and more flexible RR fibre in the blended yarn structure. Due to reduction in initial modulus, fabric’s blending length as well as flexural rigidity in weft direction (in which nettle-based yarn has been used) of the blended fabric is also reduced, as compared to the 100% nettle fabric. Figure 5 shows the tenacity vs. tensile strain of the pure nettle and nettle/RR (50/50) blended fabrics. It shows the tenacity of 50/50 nettle/RR blended fabric was lower than the 100% yarn-based fabric. As expected, with the introduction of RR fibre, the fabric strain in the weft direction also increases might be due to higher strain percentage of RR fibre.

6 Conclusions Nettle is a naturally available plant-based bast fibre, mostly grown in the Himalayan region. Presently, commercial production of nettle fibre as well as nettle fibre-based textiles are not properly available from the inventories of the major natural textile producers and traders, due to possibly unavailability of appropriate technology for harvesting stinging nettle plant, retting for extraction of quality fibre, large-scale mechanical processing for development of pure or blended yarns, and development of blended or union fabrics. In-spite of many production, extraction and processing limitations, several attempts were made in the past to produce yarn either from 100% nettle fibre or its suitable blending with various natural or synthetic fibre. Extracted fibre exhibited suitable properties viz., length, fineness, diameter, strength,

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Pure nettle fabric

50/50 Nettle/RR fabric Fig. 5 Tenacity and tensile strain curves of different nettle/RR blended woven fabrics (warp-cotton and weft-nettle or blended yarn)

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and modulus, required for making yarn and fabric. It is recommended to blend nettle fibre with other natural or synthetic fibres for making blended yarns to develop blended or union fabrics for their application in fashion apparel/ garments, handicrafts items, home textiles, and other technical end uses. Nettle fibre-based yarns of nominal count 86 tex (2.5 lb/spindle) were developed from only nettle fibre or in blending with RR fibre in the ratio of 50/50. Such yarns were used in the weft direction for developing woven fabrics. The developed fabrics were successfully used to produce apparel textile products. The information summarized in the present paper postulates, that nettle fibre, a forest waste, can be successfully utilized to develop different valueadded textiles including apparel wear. It also holds a scope of improving the livelihood of nettle plant cultivator in the Himalayan regions through appropriate technological intervention.

References 1. Ahmed Z, Akhter F (2001) Jute retting: an overview. Online J Biol Sci 1(7):685–688 2. Bacci L, Baronti S, Predieri S, Virgilio N (2009) Fiber yield and quality of fiber nettle (Urtica dioica L.) cultivated in Italy. Indus Crops Prod 29:480–484 3. Basu G, Roy AN (2008) Blending of jute with different natural fibres. J Nat Fibers 4(4):13–29 4. Bhardwaj S, Pant S (2014) Properties of nettle-acrylic blended yarn. J Text Assoc 75(1):28–31 5. Bodros E, Baley C (2008) Study of the tensile properties of stinging nettle fibers (Urtica Dioica). Mater Lett 62(14):2143–2145 6. Chattopadhyay SN, Pan NC, Roy AN, Samanta KK (2020) Pretreatment of jute and banana fibre—its effect on blended yarn and fabric. J Nat Fibres 17(1):75–83 7. Chattopadhyay SN, Pan NC, Roy AN, Samanta KK, Khan A (2021) Hybrid bleaching of jute yarn using hydrogen peroxide and peracetic acid. Ind J Fibre Text Res 46:78–82 8. Debnath S (2015) Great potential of stinging nettle for sustainable textile and fashion. In: Gardetti M, Muthu S (eds) Handbook of sustainable luxury textiles and fashion. environmental footprints and eco-design of products and processes. Springer, Singapore, pp 43–57. https:// doi.org/10.1007/978-981-287-633-1_3 9. Debnath S (2016) Natural fibres for sustainable development in fashion industry. In: Muthu S, Gardetti M (eds) Sustainable fibres for fashion industry. environmental footprints and ecodesign of products and processes. Springer, Singapore, pp 89–108. https://doi.org/10.1007/ 978-981-10-0522-0_4 10. Gahlot M, Joshi J, Bhatt P (2018) Assessment of physico-chemical properties of Himalayan nettle fibres. Pantnagar J Res 16(1):71–75 11. Garg N, Saggu KH (2017) Mapping and profile of Himalayan nettle (Girardinia diversifolia) units in Uttarakhand. Int J Home Sci 3(1):146–149 12. Gupta PK, Patra S, Samanta KK (2021) Potential of okra for application in textiles: a review. J Nat Fibres 18(11):1788–1800 13. Harwood J, Horne MRL, Waldron D (2010) Cultivating stinging nettle (Urtica dioica) for fibre production in the UK. Asp Appl Biol 101:133–138 14. Jarman CG (1987) The retting of jute. Published by FAO Agricultural Service Bulletin, vol 60, pp 1–54, USA. ISBN 92-5-101415-9 15. Kambli ND, Samanta KK, Basak S, Chattopadhyay SK, Patil PG, Deshmukh RR (2018) Characterization of the corn husk fibre and improvement in its thermal stability by banana pseudostem sap. Cellulose 25(9):5241–5257 16. Kumar N, Das D, Neckar B (2018) Effect of fiber orientation on tensile behavior of biocomposites prepared from Nettle and poly(lactic acid) fibers: modeling and experiment. Compos B 138:113–121

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17. Kumar N, Das D (2017) Alkali treatment on nettle fibers: Part I: investigation of chemical, structural, physical, and mechanical characteristics of alkali-treated nettle fibers. The J Text Inst 108(8):1461–1467 18. Majeed K, Jawaid M, Hassan A, Bakar AA, Khalil HPSA, Salema AA, Inuwa I (2013) Potential materials for food packaging from nanoclay/natural fibres filled hybrid composites. Mater Des 46:391–410 19. Mishra L, Basu G, Samanta AK (2017) Effect of chemical softening of coconut fibres on structure and properties of its blended yarn with jute. Fibers Polym 18(2):357–368 20. Mudoi MP, Sinha S, Parthasarthy V (2021) Polymer composite material with nettle fiber reinforcement: a review. Bioresour Technol Rep 16:100860 21. Pankaj JC, Kant S (2022) Study on mechanical properties and delamination factor evaluation of chemically treated nettle fiber reinforced polymer composites. J Nat Fibers. https://doi.org/ 10.1080/15440478.2022.2135053 22. Radhakrishnan S, Preeti A (2015) Development of fabric from Girardina Diversifolia stem fibres and its blends. Int J Innov Res Sci, Eng Technol 4(11):10499–10506 23. Roy AN, Samanta KK, Patra K (2019) Physico-chemical properties of black yak fibre and its modification for blending with jute fibre. J Nat Fibres 16(2):225–236 24. Sabir EC, Unal BZ (2017) The using of nettle fiber in towel production and investigation of the performance properties. J Nat Fibers 14(6):781–787 25. Samanta KK, Basak S, Chattopadhyay SK (2017) Environmentally friendly denim processing using water-free technologies. In: Muthu SS (eds) Sustainability in denim. Elsevier & Woodhead Publishing, pp 319–348. https://doi.org/10.1016/B978-0-08-102043-2.00012-5 26. Samanta KK, Basak S, Chattopadhyay SK (2016) Potential of Ligno-cellulosic and protein fibres in sustainable fashion. In: Muthu S, Gardetti M (eds) Sustainable fibres for fashion industry. environmental footprints and eco-design of products and processes. Springer, Singapore, pp 61–109. https://doi.org/10.1007/978-981-10-0566-4_5. 27. Samanta KK, Joshi AG, Jassal M, Agrawal AK (2021) Hydrophobic functionalization of cellulosic substrate by tetrafluoroethane dielectric barrier discharge plasma at atmospheric pressure. Carbohyd Polym 253:117272 28. Samanta KK, Roy AN, Baite H, Debnath S, Ammayappan L, Nayak LK, Singha A, Kundu TK (2021) Applications of nettle fibre in textile: a brief review. Int J Bioresour Sci 08(01):39–45 29. Samanta KK, Roy AN, Baite H, Debnath S, Ammayappan L, Nayak LK, Singha A, Kundu TK (2023) Properties of Himalayan nettle fibre and development of nettle/viscose blended apparel textiles. J Nat Fibers 20(1):1–17, 2183924 30. Sett SK, Banerjee S, Mukhopadhaya A (2015) Studies of nettle (Girardinia Diversifolia) fibre blended Yarns. In: 2nd international conference on natural fibres- from nature to market. Azores, Portugal, pp 1–6. https://www.researchgate.net/publication/276025302_Studies_of_ Nettle_Girardinia_Diversifolia_fibre_blended_Yarns 31. Shaolin X, Hong S, Fengli H, Aiming X, Xiaoyin S (2005) Technology research on friction spinning nettle core-spun yarn. Cotton Text Technol 9:13–15 32. Srivastava N, Rastogi D (2018) Nettle fiber: Himalayan wonder with extraordinary textile properties. Int J Home Sci 4(1):281–285 33. Sunny G, Rajan TP (2021) Review on areca nut fiber and its implementation in sustainable products development. J Nat Fibers 1–15. https://doi.org/10.1080/15440478.2020.1870623 34. Suryawan IA, Suardana NPG, Winaya IS, Suyasa IB, Nindhia TT (2017) Study of stinging nettle (urtica dioica l.) fibers reinforced green composite materials: a review. IOP Conf Ser: Mater Sci Eng 201(1):012001 35. Teli MD, Pandit P, Samanta KK (2015) Application of atmospheric pressure plasma technology on textile. J Text Assoc 75(6):422–427 36. Thilagavathi G, Karan CP (2018) Investigations on oil sorption capacity of nettle fibrous assembly and 100% nettle and nettle/kapok blended needle-punched nonwovens. J Indus Text 49(40):415–430 37. Zuo GUO, Hailiang WU, Xiaoyin SUN (2006) The research on spinnability of the nettle fibers. J Northwest Inst Text Sci 5(2):139–142

A Study on the Application of Weaver Ant Silk in Wound Healing P. Kandhavadivu, S. Sudha, and B. Charmini

Abstract Silk produced by weaver ants is a naturally available non-woven fibroinbased nanofiber. Weaver ant larvae extrude proteins in the form of hollow nanofibers, which the adult ants use to build their nests. Weaver ant silk is a protein-rich substance, and protein aids in wound healing. It also has a high level of chemical resistance. Even though it has a diameter of only a few nanometres, it is also hollow in nature, making it a unique fiber of existence. Because it has the capacity for wound healing and uniform drug release, drugs can be loaded to speed up the healing process. In this research work, the weaver ant silk protein is extracted and tested for its potential in wound healing by means of wound scratch assay and drug release rate. In-vitro wound scratch assay test showed 74% wound healing in 100 μl concentration of the weaver ant protein. Drug release test showed gradual delivery of drug from weaver ant silk membrane at 1.36% in one hour to 7.89% in 12 h, proving its ability to withhold any drug and release it slowly. Keywords Weaver ant silk · Wound scratch assay · Drug release rate · Wound healing · Nano fiber

1 Introduction Silks are a form of protein made up of a specific set of amino acids. A variety of insects and arachnids manufacture silk for a variety of reasons, including cocoon formation and nest building. They are widely used in biomaterials and bio-medical applications due to their physical, mechanical, and biological properties, such as strength, lightweight, toughness, elasticity, biocompatibility, biodegradability, minimal inflammatory reaction, ability to promote healing, and ease of chemical modification to suit the application [1–5]. P. Kandhavadivu (B) · S. Sudha · B. Charmini Department of Fashion Technology, PSG College of Technology, Peelamedu, Coimbatore, Tamilnadu 641004, India e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024 D. Gupta et al. (eds.), Functional Textiles and Clothing 2023, Springer Proceedings in Materials 42, https://doi.org/10.1007/978-981-99-9983-5_16

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Wound dressing and tissue engineering of bone tissue, cartilage tissue, ligament tissue, tendon tissue, hepatic tissue, connective tissue, endothelial tissue, and blood vessels have been achieved using films, sponges, hydrogels, and non-woven mats made from silk fibroin extracted from domestic silkworm (B. Mori) cocoons and recombinant fibroin produced by bacterial cells. Spider silk fibroin was effectively used to make a composite fibroin-based fibrous non-woven mat (Nephila clavipes) [6, 7]. Silk produced by weaver ants is a naturally available non-woven fibroin-based nanofibers with average diameter of 766 nm. Weaver ant larvae extrude proteins in the form of hollow nanofibers, which the adult ants use to build their nests [8]. A weaver ant is known for its exceptional architecture skills of nest formation and teamwork greatly contributing to their survival. The membranes have excellent properties like light weight, hollow structure, resistance to disease, and hydrophobic nature discovered in previous studies extending weaver ant silk’s potential uses in medical applications and variety of scientific domains. Weaver ant silk is a proteinrich substance, and protein aids in wound healing. It also has a high level of chemical resistance [1–3, 8]. It is similar to the morphology of fibrous scaffolds used in tissue engineering and wound healing [9].

2 Nest Construction The Asian weaver ant (Oecophylla smaragdina) is a dominating arboreal ant found across tropical Asia [1, 10]. These ants construct intricate nests in the canopy, which are usually scattered across numerous trees to create a single colony, with hundreds of ants in each nest and thousands of ants in a colony. Worker ants of O. smaragdina, weave silk from their larvae into the leaves of the host plant (Fig. 1). Nest construction is done by worker ants, which collaborate to pull the leaves together using their mandibles, but if the two leaves are not in reach, many ants hold one another to form a chain and pull the leaves together. Then the other ants bring the larvae and commence to sew the leaves using those larvae. One or few ants come from the interior of the leaves and hold the larvae with their mouth. The larvae then secrete a filament of silk, which is then fixed to the edge of leaves with their mouth. The ant then runs towards the other end drawing the filament and fixing it there, thus it goes forward and backward again and again until the leaves are strongly bound together. Likewise, they join many leaves together and form a collective nest for their colony [11–14]. Weaver ant nests feature a distinctive architecture, consisting of small sections of web tied together by bonding fibers and interlacing the fibers in a manner comparable to the selvage of woven fabrics. The nests of weaver ants are white to pale yellow in colour and have a uniform thickness ranging from 20 to 40 μm [1, 2, 8]. Ant larvae mats are in the form of a mesh and are formed by uniform nanofibers that even a highly electrically spun fiber is unable to achieve [15, 16]. The membranes withstand rigorous boiling in weak alkali, show good attachment and proliferation of

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Fig. 1 Nest construction by weaver ants; Ants collaborate to pull the leaves together and using larvae bind the leaves to complete the nest

osteoblasts and can load up to 4.7 times higher drugs compared to common silk. The tensile characteristics of ant nanofiber membranes are superior to those of any electrospun protein nanofiber membrane. The ant nanofiber membranes include amino acids with high concentrations of amine and hydroxyl groups, allowing for easy membrane modification for various applications. Interestingly, the water wettability of old and freshly produced fibers differ, which is noteworthy for its potential applications [6, 7, 17, 18]. Weaver ant’s silk can be considered as a good example of a biopolymer. These protein-based biopolymers are porous, flexible, eco-friendly, lightweight, and exhibit excellent mechanical and chemical properties and disease-resistant properties. Naturally obtained polymers are biodegradable with high biocompatibility and minimal inflammatory reaction. This biopolymer is hydrophilic when freshly woven between leaves and later it becomes hydrophobic [2, 18]. Therefore, if some hazardous residues normally formed in the fibers could be eliminated, the natural weaver ant fibrous mat could serve as a good scaffold for cell adhesion and growth. As a result, the ant nanowebs are unique protein nanofiber substrates with features suited for tissue engineering and other medical applications due to their cytocompatibility and good tensile properties, particularly the wet strength [18]. Many studies have been published recently on the use of silks produced by B. Mori silkworms and spiders in tissue engineering and other health-care applications

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[9, 15, 16], but only a few papers have been published on the use of weaver ant larvae’s silk filaments in healthcare applications. In this research work, a complete research on the morphology, properties, composition, and characteristics of weaver ant silk, as well as its use in wound dressing applications have been studied.

3 Materials and Testing Methods The weaver ant silk was extracted from trees and the protein was isolated to remove the toxicity present in the fiber. The prepared sample was tested for the viability in wound healing using in vitro study, and also the drug release property was studied. Antimicrobial activity of the developed membrane was tested by agar well diffusion method. The diameter of the zone of inhibition was measured against the microorganism of P.acne, S.aureus, S.epidermidis, and K.pneumoniae. The nano structure of the web was studied through SEM analysis. The potential for wound healing of the weaver ant sample was tested by means of wound scratch assay. A wound scratch assay is a standard In vitro technique used to measure the cell migration and wound healing. The process involves four main steps such as, culture preparation, scratch making, data acquisition of scratch images for time lapse, and data analysis of scratch closure. Cells are grown together in a monolayer and a scratch is made using a pipette tip, which creates a wounded area. Scratch closure images are captured at regular intervals using optical microscopy. Once the gap is closed, the images are compared to quantify the migration rates of the cells. Drug release rate was tested for the evaluation of dosage under standardized in vitro settings that provide insight on the in vivo performance of the drug. The phosphate buffer saline was prepared with the pH of 6.5 and negative control was prepared by mixing 50 μg of AgONP with PBS buffer. The positive control was prepared by adding AgONPs coated silk with PBS buffer. These prepared samples were incubated at 37 °C for standard time and drug release rate was measured using UV spectrometer at 450 nm.

4 SEM Analysis The Scanning Electron Microscope (SEM) image of the weaver ant fiber shows the nanostructure of the weaver ant fiber. SEM images at different magnifications of × 1000, ×5000, ×10,000, and ×30,000 with same voltage of 20 kV of varying scales of 0.5 μm, 1 μm, 5 μm, and 10 μm confirm the structure of nanofiber as smooth and consistent. From the figure it is observed that the fibrous assembly consists of connecting nanowebs formed by means of several layers of web that interlace with each other. This structure is similar to the nanofibers made out of manmade fibers that are used in tissue engineering as scaffolds and for wound healing purposes. From

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Fig. 2 SEM images at different magnifications of a ×1000, 10 μm b ×5000, 5 μm c ×10,000, 1 μm and d ×30,000, 0.5 μm with same voltage of 20 kV

recent studies it was observed that the weaver ant nanofiber membranes had average diameters of 766 ± 326 nm. The average thickness, mass, and apparent density of the fibrous mat were 39.0 ± 9.8 m, 0.8 ± 0.1 mg/cm2 , and 0.22 ± 0.03 g/cm3 , respectively [8] (Fig. 2).

5 Composition of Weaver Ant Web The weaver ant fiber is composed of 77% of fibrous materials, 20% to 22% gummy substances, 1.5% fat and wax material, and 1.5% other substances, which can be toxic to the fibroblast cells. Therefore, to eliminate these toxic substances, degumming must be carried out after the extraction of fiber. Some of the major amino acids present in the collected weaver ant sample are Glycine -5.29, Alanine-26.3, Glutamic acid-14.76, Serine-15.04 and Tyrosine, Leucine, Arginine, Valine, Threonine are few of the other minor components. Amino acid is considered to be the building block of protein that is used by all the cells present in our body. Amino acid in general builds the protein that is essential for the survival of the human being. It is responsible in building and repairing the body

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tissues especially in wound healing process. The nanofibers produced by ant larvae are proteins, and the proteins produced by weaver ants have a coiled-coil structure rather than the helical form found in typical silks, according to research. The fibers formed by the weaver ant’s larvae are found to have hollow cross-section joined by glue secretions of the ant. The presence of higher hydrophobic side chains and more hydroxyl groups is the major advantage of ant protein over other protein types. As a result, the ant protein shows a strong interaction with negatively charged materials or chemicals, making it ideal for biomedical applications (such as implants and filters), as well as a suitable material for controlled drug release. The existence of more amine and hydroxyl groups is the key factor enabling ant protein to rapidly adapt/use in multidisciplinary applications [2, 18, 19].

6 FTIR Analysis FTIR spectroscopy of the weaver ant silk structure is used to determine the molecular structure of the protein. FTIR spectra of natural weaver ant fibers reveal the absorption bands at 2960 cm−1 (C–H structure), 1658 cm−1 (amide I; attributed to random coil conformation), 1546 cm−1 (amide II; assigned to β-sheet structure). The values are found closer to the FTIR results of previous studies. The existence of α-helical, anti-parallel and parallel β-sheets, and random coil configurations in the protein of interest can be associated with both the shape and position of band frequencies. FTIR peak at 1151 cm−1 represents C–O stretching frequency [5] and the peak at 1546 cm−1 indicates the appearance of the amide group in line with the chitosans that are not completely deacetylated I [15]. The deformation of the amide I band or C = O deformation is represented by the peak at 1658 cm−1 . The peak at 2960 cm−1 indicates the C-H stretch of the structure. These peaks indicate the presence of the group that is in line with the chitosan used for the wound dressing matrices [17] (Fig. 3).

7 Fiber Extraction and Protein Isolation Fibre was extracted from the collected weaver ant nest and washed with water. The washed fiber sample was soaked in 0.8% sodium chloride solution to remove the gummy substances and other impurities. The soaked sodium chloride solution was incubated for 1 h at 45 °C and then ground to obtain crude protein. The crude protein was then added with equal volume of unsaturated ammonium sulphate and the solution was incubated overnight at 4 °C. The solution was further centrifuged at 5000 rpm for 5 min. The pellets were collected from the solution and dissolved in phosphate buffer saline (PBS) [20] (Fig. 4).

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Fig. 3 FTIR analysis of the sample

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d

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Fig. 4 Protein isolation a Weaver ant mesh soaked in NaCl b Incubated at 45 °C for 1 h c Grinding d Crude protein e Centrifuge at 5000 rpm for 5 min f Protein pellets of 1 mg each

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a

b

Fig. 5 a Synthesized dry silver nanoparticles b Silver nanoparticle coated weaver ant silk membrane

8 Synthesis of Silver Nanoparticles One ml of protein extract was mixed with prepared 0.1 M silver nitrate solution and incubated at 60 °C overnight. Then the solution was centrifuged at 10,000 rpm for 10 min for pellet formation. The pellets were collected and washed with methanol and these two processes were repeated 3 times. The collected nanoparticles were further crushed and washed in methanol [17]. The silver nanoparticles as shown in Fig. 5 were obtained after incubating it at 60 °C. These silver nanoparticles were coated over the weaver ant silk membrane by means of dip and dry method and allowed to dry in an incubator at 60 °C.

9 Antimicrobial Activity The silver nanoparticle coated weaver ant protein sample was tested for antimicrobial activity against the major constituents in wound infections such as S.Epidermis, K.Pneumaniae, S. aureus, and P.Acne and the results are shown in Fig. 6. The silver nanoparticle coated weaver ant protein sample and commercial drug sample show higher zone of inhibition when compared to protein extract. The commercial drug and silver nanoparticles show similar kind of inhibition to all the microbes. The increased inhibition by the nanoparticles than the protein extract is because the silver nanoparticles combat bacterial microbes through multiple mechanisms that are simultaneously active. It includes disruption of bacterial cell membrane, generation of reactive oxygen species, penetration of the bacterial cell membrane, and induction of intracellular antibacterial effects that involve interactions with DNA and proteins [21].

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Fig. 6 Antimicrobial activity of the extract against a S. Epidermidis; b K. Pneumaniae; c S. Aureus; and d P. Acne

10 Wound Scratch Assay The details of the test performed are as follows, Source of cell line: NCCS, Pune. Justification: L929 is an established and well-characterized cell line that has demonstrated reproducible results. Culture media: MEM medium supplemented with fetal bovine serum. Incubation: 37 °C with 5% CO2 . Assay Method: Wound Scratch Assay.

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Fig. 7 In-vitro wound scratch assay cell line: L929; Sample name: Protein

Table 1 Wound scratch assay, concentration with its healing percentage Concentration(μg/μl)

Wound area (μm)

% of wound healing

25

2269

61

50

2473

65

75

2227

69

100

2485

74

Imaging: Inverted Phase Contrast Microscope (Fig. 7). From the test results, it is observed that the wound healing percentage at 25 μl, 50 μl, 75 μl, and 100 μl concentrations are 61%, 65%, 69%, and 74% respectively. Hence the given sample protein heals the wound in L929 cells after 24 h at 100 μl concentration (Table 1).

11 Drug Release Rate Test Drug release test was performed using UV spectroscopy to prove that the weaver ant silk has good drug release due to its nano and hollow fiber structure. From the results, it is observed that the release of the drug is linearly increasing with time. The UV spectrometer reading taken at 0, 1, 3, 6, and 12 h shows a drug release percentage of 0, 1.36, 1.87, 5.16, and 7.89 respectively. The test result shows that the weaver ant fiber has gradually increasing and uniform drug release property, which is shown in the graph. The test result proves that the naturally available weaver ant silk has a good potential for wound healing and drug releasing property and hence can enhance the wound healing process.

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Time (h) Fig. 8 Drug release percentage with respect to varying time

Controlled drug release is more suitable for wound healing as it provides a safe and efficient treatment environment. The acute release of drugs leads to unwanted side effects [9] and slow release will reduce such side effects. It is also found that for the wound healing property, the controlled drug release will provide a better wound management. This is mainly because the sustained release of drugs reduces the administration frequency and provides continual therapeutics at the site of wound that gradually assist healing [22] (Fig. 8).

12 Conclusion Weaver ant silk protein was extracted, characterized, and analyzed for its potential in wound healing process. The SEM image and FTIR results depict its nano structure and suitability for wound healing applications. The antibacterial activity tested against K.Pneumaniae, S. aureus and P.Acne and S.Epidermis showed that there is less antibacterial property for the protein extract, but the silver nanoparticle coated weaver ant silk exhibited antibacterial property against all four bacteria. In vitro wound scratch assay test showed 74% wound healing in 100 μl concentration of the weaver ant protein. Drug release test showed gradual delivery of drug from weaver ant silk membrane at 1.36% in one hour to 7.89% in 12 h, proving its ability to withhold any drug and release it slowly. Hence this study proves that the weaver ant silk has a good potential for wound healing property and hence can enhance the healing process.

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References 1. Reddy N, Yang Y (2015) Unique silk fibres from Weaver ant, innovative biofibers from renewable resources. Springer Materials 2. Reddy N, Xu H, Yang Y (2011) Unique natural-protein hollow nanofiber membranes produced by weaver ants for medical applications. Biotechnol Bioeng 108:1726–1733 3. Prajwal M, Sangamesha MA, Pushpalatha K (2015) Ant larvae silk fibres mat. Curr Sci 108(8):1544–1547 4. Selvaraj S, Fathima NN (2017) Fenugreek incorporated silk fibroin nanofibers-a potential antioxidant scaffold for enhanced wound healing. ACS Appl Mater Interf 9:5916–5926 5. Shan YH, Peng LH, Liu X, Chen X, Xiong J, Gao JQ (2015) Silk fibroin/gelatinelectrospun nanofibrous dressing functionalized with astragaloside IV induces healing and anti-scar effects on burn wound. Int J Pharm 479:291–301 6. Saravanan D (2006) Spider silk: structure, properties and spinning. J Text Apparel Technol Manag 5(1):1–20 7. Chutipakdeevong J, Ruktanonchai UR, Supaphol P (2013) Process optimization of electrospun silk fibroin fiber mat for accelerated wound healing. J Appl Polym Sci 3634–3644. https://doi. org/10.1002/app.39611 8. Siri S, Maensiri S (2010) Alternative biomaterials: natural, non-woven, fibroin-based silk nanofibers of weaver ants (Oecophyllasmaragdina). Int J Biol Macromol 46:529–534 9. Goonoo N, Bhaw-Luximon A, Jhurry D (2014) Drug loading and release from electrospun biodegradable nanofibers. J Biomed Nanotechnol 10:2173–2199 10. Sekar D, Dhanamoorthy M (2019) Chacko VijaiSharmaBiofabrication of silver nanoparticles using the aqueous extract of weaver ant’s nest. Int J Pharm Biol Arch 10(4):275–280 11. https://science.thewire.in/the-sciences/weaver-ants-silk-larvae-kin-selection-altruism/ 12. Peerzada N, Pakkiyaretnam T, Renaud S (1990) Volatile, Oecophyllasmaragdina. Agric Biol Chem 54(12):3335–3336 13. Peng RK, Christian K, Gibb K (1998) How many queens are there in mature colonies of the green ant, Oecophyllasmaragdina (Fabricius). Aust J Entomol 37(3):249–253 14. Van Mele P (2008) A historical review of research on the weaver ant Oecophylla in biological control. Agric Forest Entomol 10(1):13–22 15. Liang D, Hsiao BS, Chu B (2007) Functional electrospun nanofibrous scaffolds for biomedical applications. Adv Drug Deliv Rev 59:1392–1412 16. Rošic R, Kocbek P, Pelipenko J, Kristl J, Baumgartner S (2013) Nanofibers and their biomedical use. Acta Pharma 63:295–304 17. Zhou S (2008) Preparation and characterization of a novel electrospun spider silk fibroin/ poly(D, L-lactide) composite fibers. J Phys Chem B 112:11209–11216 18. Murugesh BK (2017) Silk from silkworms and spiders as high-performance fibers. In: Bhat G (ed) Structure and properties of high-performance fibers, pp 327–366. Woodhead Publishing, Oxford 19. Bradshaw JWS, Baker R, Howse PE (1979) Chemical composition of the poison apparatus secretions of the African weaver ant, Oecophyllalonginoda, and their role in behaviour”. Physiol Entomol 4(1):39–46 20. Khamhaengpol A, Maensiri S, Siri S (2010) Fibroin protein extract from red ant nests for a production of electrospun nanofibers. KKU Res J 15(10):919–929 21. Satya Madhuri P, Himaja S, Shreenivasulu K (2017) A comparative study on cytocompatibility of weaver ant nest fibre mats. World J Pharm Pharm Sci 6(7):1496–1508 22. Maver T, Hribernik S, Mohan T, Smrke DM, Maver U, Stana-Kleinschek K (2015) Functional wound dressing materials with highly tunable drug release properties. RSC Adv 5:77873–77884

Study on the Rustling Sound of Various Fabrics and Their Properties V. Prithvi, R. Priyanka, N. Sadvika, and S. Sundaresan

Abstract In the textile industry, there is a thriving attentiveness to the use of certain types of fabric among people. The sound produced due to the rustling of these fabrics varies according to diverse parameters. Fabric sound is contemplated as a disturbance in certain circumstances to the user. The disturbance due to sound brings about irritability, loss of concentration, and anxiety, and affects the sensorial clothing comfort of humans. The sound created due to abrasion of the fabric itself or with other surfaces during its usage, is dependent on various physical and chemical parameters of the fabric. The main purpose of this study is to evaluate the rustling sounds established by different woven fabrics made of nylon, silk, polyester, and polyester/ cotton blended fabrics. This research assesses the rustling nature of different types of fabrics based on GSM, structure, Type of fiber, flexural rigidity, and drape. Keywords Sensorial comfort · Rustling sounds · Flexural rigidity

1 Introduction In the textile research field, researchers are keen on sensory evaluations related to vision, olfaction, and audition [1]. Fabric’s objective measurements such as drape, tactility, lustre, and odour have been in consideration for over the decades in the manufacturing industry, but in the case of fabric rustling sound, there is no deep concern, which is also the key factor that affects the sensorial comfort of clothing. Fabrics coated for water repellency and wind-proof make considerable noise that bothers consumers and others in some situations. On the other hand, the sound of some fabric can provide a person with aesthetic satisfaction. The rustling of silk for women’s clothes can be a desirable attribute that pleases consumers. There are commonly three types of noise: internal, external, and semantic, in some cases some fabric absorbs noise, and the rest emits noise. Mostly acoustic material absorbs sound. V. Prithvi (B) · R. Priyanka · N. Sadvika · S. Sundaresan Department of Textile Technology, Kumaraguru College of Technology, Coimbatore-641 049, Saravanampatti, Tamil Nadu, India e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024 D. Gupta et al. (eds.), Functional Textiles and Clothing 2023, Springer Proceedings in Materials 42, https://doi.org/10.1007/978-981-99-9983-5_17

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Table 1 Characteristics of specimen Type of fabric

Fiber content

Yarn type

Fabric construction/name End usage

Nylon (F1)

Nylon

Filament

Plain

Swimwear

Silk (F2)

Silk

Filament

Plain

Blouse

Polyester (F3)

Polyester

Filament

Plain

T-shirt

Polyester/cotton (F4) Polyester–30% Blended yarn Plain Cotton—70%

Bed cover

In the case of various differential parameters, researchers are attempting to find relationships between sound and the structural parameters of fabrics such as fibre content, cross-sectional shape, fabric construction, smoothness, sensorial comfort, auditory sensibility, and finishing such as anti-microbial finish, etc. However, the characteristics and properties differ for woven fabric and knitted fabric with respect to their structure, shape, elongation, strength, etc. In this context, we have taken both knitted and woven fabrics. In most studies related to sound parameters, researchers used the basic principle which focuses on Zwicker’s psychoacoustic parameters—loudness, sharpness, roughness, and fluctuation—to rustling sounds. And the research of rustling sounds of various fabrics was seldom seen.

2 Material Nylon, Polyester, Silk, Polyester/Cotton, DC motor, PLC (programmable logic controllers), Drive, Nylon Shaft, Nylon Cylinder, Decibel meter. All the described fibres have constituent length, fibre strength, uniformity, fineness, and elongation. (a) (b) (c) (d) (e)

Nylon- Weave—plain, Thickness—10 mm, gsm—75 Silk—weave—plain weave, thickness—0.140 mm, gsm—70.80 Cotton is a constituent fibre that blends and corresponds with polyester well. Polycotton—weave—plain, thickness—4.5-inch, gsm—95 Polyester—weave—plain, thickness—0.2 mm, gsm—170 (Table 1).

3 Method The rustling sound of fabrics is measured using a simple mechanical concept. Here two same or different types of fabric come in contact to produce the sound. This sound is determined with a compact instrument of 50 cm * 30 cm. This instrument consists of 2 parts, one consists of DC motor, PLC, and Drive whereas the other part consists of a nylon cylinder, a decibel meter, and 2 fabrics. The sound produced by the motor does not transmit to other parts of the instrument. A glass shield of width

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5 mm is situated in between the two parts in addition to an acrylic sheet. A hollow nylon cylinder is wound with fabric ‘F1’ in the anti-clockwise direction. One end of the fabric ‘F2’ is stretched straight above the cylinder and the other end of the cloth has been drawn over the cylinder and stretched to the bottom of the base. This would form a bent curve where both the fabrics would come in contact and produce sound when the cylinder is rotated continuously at a constant speed (Figs. 1 and 2). The velocity of the cylinder at which it is rotated plays a major role. The power from the DC motor is transmitted to the cylinder through a nylon shaft. The other end of the shaft is in a ‘D’ shape connected to the cylinder, which prevents slippage. The speed of the DC motor is controlled with a Programmable Logical Controller (PLC) with the help of a drive. The input speed can be varied according to the fabric. The speed of the cylinder and the mechanical property of fabric determine the amount of sound produced. The sound is measured by a decibel meter and tabulated.

Fig. 1 Top view of the instrument

Fig. 2 3D model of the instrument

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Table 2 Preliminary sample test for various Fabrics Type of fabric

Thickness (mm)

GSM (grams/sq. meter)

Abrasion

Crease (degree)

Stiffness (bending length) in cm Warp way

Weft way

Sound in decibel

Nylon

0.113

67.44

0.001

111

3

3.5

26.48

Silk

0.140

70.80

0.0019

105

2.3

3.3

13.76

Polyester

0.123

64.64

0.0004

121

1.9

1.8

17.68

Polyester/ cotton

0.212

82.47

0.0015

130

2.0

2.1

10.32

4 Result The preliminary study results of the different fabric types are tabulated below. Based on the preliminary study it has been noted that the rustling sound of nylon is higher when compared to others. This is likely due to more roughness of the fabric and friction force between contact surfaces. The lower decibel value observed for the polyester/cotton blend may suggest that this fabric produces less sound due to its lower physical properties compared to other fabrics. However, it is important to note that the specific results of the study may depend on the methodology used and the fabrics that were tested. Overall, the study provides insight into the sound properties of different fabrics and how they are affected by their physical properties (Table 2).

5 Conclusions This study was carried out to examine the psychoacoustic characteristics of four different fibres, and their composition and to identify their relationship with physical sound parameters. The sound levels of the fabric have been affected by various factors such as roughness, shear, and bending. In the consideration of polyester and nylon, both have more similar properties with slight variations due to physical characteristics. Sound from each fabric was recorded. Most of the water-repellent and windproof materials such as parachutes, sports materials, sleeping bags, trekking tents, and military apparel which are made specially to withstand high climatic changes and weather can also be studied for their sound parameters in the further proceedings.

Reference 1. Kim C, Cho G, Na Y (2002) Effects of basic weave differences in silk fabric and yarn type variations in satin weave on sound parameters. Text Res J 72(6):555–560

Development of Flax and Silk Blended Yarn in the Wet Spinning System and Comfort Characterization of Blended Fabrics Brojeswari Das, Sreenivasa, Y. C. Radhalakshmi, S. K. Som, and A. T. Bindu

Abstract Flax fibre obtained from the flax plant, is one of the oldest and most traditional fibres, valued for its exceptional coolness and freshness in hot weather. Silk fibre, known as the queen of textiles, is valued for aesthetics and comfort. Different types of silk produced in India, are known for their unique characteristics. Due to high stiffness flax fibres are spun into yarn in a wet spinning system, whereas silk fibre spinning is done in a worsted spinning system. In the present study, work has been done to develop silk and linen blended yarns in a wet spinning system. For running silk along with flax fibre in a wet spinning system, certain modification in the spinning conditions has been done. Three types of silk fibres, i.e., mulberry, eri, and tasar have been used in different proportions for this purpose. The developed yarns have been subjected to quality testing. The effect of silk proportion on yarn properties and comfort properties of fabric has been evaluated. The study deciphers that silk/linen blends can be developed in a wet spinning system. Experimental results show that linen/silk blends can offer excellent comfort properties to the wearer with a superior appearance. Keywords Linen spinning · Silk blends · Comfort properties

1 Introduction Flax/Linen is a natural bast fibre, known for its high fluid absorption capacity. Garments made of linen are valued for their exceptional coolness and freshness in hot weather. Silk is a natural protein fibre, known for its aesthetic; it is also considered comfortable to the wearer for both summer and winter seasons. It behaves well as summer wear due to its lightweight, good wicking, absorbency, and low qmax to qs B. Das (B) · Sreenivasa · Y. C. Radhalakshmi · A. T. Bindu Central Silk Board, CSTRI, Madiwala, Bangalore, India e-mail: [email protected] S. K. Som Global Textile: Consultant and Services, Thane, Mumbai, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024 D. Gupta et al. (eds.), Functional Textiles and Clothing 2023, Springer Proceedings in Materials 42, https://doi.org/10.1007/978-981-99-9983-5_18

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ratio, which indicates cool at the touch and good water vapour permeability [1]. It holds a good place to protect the wearer from wind and cold too, due to its better cover and low air permeability [2]. India is the only country which produces all four varieties of silks, namely mulberry, eri, muga, and tasar. Mulberry silk is known for its smoothness and lustre. Eri silk is known as ahimsa silk, it is known for providing warmth of wool and softness of silk. Muga is known for its shine and golden colour. Tasar is known for its elegance and rustic appearance. It has exceptionally good thermoregulatory properties. In a study by Das et al. [2], it has been observed that linen and silk both show similar thermal properties, i.e., thermal absorption and insulation. The present study work aims to explore the effect of blending silk with linen on its aesthetic comfort properties. As how well the blending will influence the absorption and permeability properties, has also been studied. Flax and silk fibres used in this research work have long staple lengths. Due to high stiffness flax fibres are spun into yarn in a wet spinning system, whereas silk fibre spinning is done in a worsted spinning system. In a work by Behera and Mishra silk linen (80:20), blended yarn was developed in the worsted spinning system [3]. When flax fibre is subjected to dry spinning, excessive hairiness is observed. In this study silk and linen blended yarns have been developed in a wet spinning system. For running silk along with flax fibre in a wet spinning system, certain modification in the spinning conditions has been done. Due to the coarseness and stiffness of flax fibre, yarns are subjected to a strong bleaching action to reduce the stiffness [4]. In wet spinning, the bleaching is done in the roving form. Strong bleaching agents will damage silk fibre when the silk has been blended with flax fibre. Hence modification was carried out in the bleaching process. Three types of silk fibres, i.e., mulberry, eri, and tasar have been used in different proportions to blend with flax fibre. Along with 100% linen yarn, 70:30- linen: silk and 50:50-linen: silk have been developed. The blending has been done in the draw frame stage.

2 Materials and Methods 2.1 Materials Slivers of flax fibre, eri, tasar, and mulberry silk fibre have been used as input material. The properties of the fibre used in this study have been given in Table 1. Silk-cut cocoons, defective cocoons (which can’t be reeled), and reeling waste are used for spinning purposes, in the case of mulberry and tasar silk, whereas eri silk cocoons are used only for spinning due to their open-mouth nature. Cocoon/reeling waste is degummed and opened for sliver preparation purpose, and flax, eri, tasar, and mulberry sliver have been procured and used for spinning purpose. Slivers of different fibres and cross-sectional images of the used fibres have been given in Fig. 1. Flax fibre before scouring and bleaching is having very high strength and coarseness, whereas its elongation is very low compared to silk fibres. Among these three

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Table 1 Properties of fibres, used for spinning Fibre type

Tenacity (g/tex)

Flax

54

Eri silk

23

Mulberry silk

25.5

Tasar silk

15.2

Elongation (%)

Fibre fineness (microns)

Avg. fibre length (cm)

1.7

20–48

22.3

13.3

12–30

14.9

7.6

10–21

15.9

11.8

17–50

16.45

Fig. 1 Images of different fibre and their cross-section. Flax fibre, (b) Eri Silk, (c) Tasar silk, (d) Mulberry silk

silk fibres, mulberry is the finest, followed by eri and tasar. The coarseness of tasar silk is similar to flax fibre. Mulberry silk has a triangular cross-section; eri silk and tasar silk fibres are having a flat microstructure, which offers a better cover. In terms of softness, mulberry is followed by eri and tasar.

2.2 Methods Yarn Preparation. Spinning of linen and silk linen blended yarns have been done in Flax wet spinning m/c at RLCL, Amravati, Maharashtra. The flow chart of the spinning process is shown in Fig. 2. After sorting and hackling of flax fibres in the

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draw frame, flax sliver was blended with silk fibres. Two blends have been developed, linen: silk—70:30 and 50:50. Difficulties were encountered in yarn preparation for silk proportions more than 50. The original colour of flax is brown, and it is very stiff in nature. Once the roving is prepared, it is subjected to a strong bleaching action to reduce the stiffness [4]. Strong bleaching action will damage silk fibre when the silk has been blended with flax fibre. Hence, while developing the linen/silk blend, the bleaching and scouring process used for linen roving has been modified. In case of the linen silk blend total duration of the process was reduced compared to the 100% linen bleaching process. In the case of 100% linen, caustic soda is used as a scouring agent, in the case of blend soda ash was used and hydrogen peroxide is used as a bleaching agent. The recipe used for the linen/silk blend is given in Table 2. Once the bleaching is done, roving is subjected to ring spinning and the spinning is done in wet conditions followed by drying of yarn in an RF dryer. Details of the yarn produced are given in Table 3. The developed yarns have been subjected to quality testing followed by fabric preparation. Fabric Preparation. Yarns of 80 Lea prepared with linen, eri silk, mulberry silk, and tasar silk fibre have been used for fabric preparation. Fabrics have been prepared on the Rapier loom by changing the weft yarn and keeping the warp same (mulberry silk filature yarn). The details of the developed fabric samples are given in Table 4. Developed fabrics have been subjected to testing of different properties. Testing Methods Yarn Parameter. The spun yarns were tested for the following particulars. 1. Blend analysis has been done by AATCC 20A 2021 testing method. 2. Yarn evenness and imperfection have been measured using USTER tester 5.

Fig. 2 Flowchart of the spinning process

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Table 2 Recipe of scouring cum bleaching process of Linen/silk blend Chemicals used

Dosage %

Cycles

Sequestering agent

0.99

1st wash

Wetting agent

1.10

Sequestering agent

0.66

Wetting agent

0.55

Stabilizer for peroxide

1.65

Scouring agent (Soda Ash)

7.00

Bleaching agent (Hydrogen Peroxide)

12.00

Cycle time–40 min 2nd wash ( Bleaching)

Cycle time–160 min Hot wash

3rd wash Cycle time-25 min

Neutralizing agent (acetic acid)

0.70

Peroxide killer (enzyme)

0.50

4th wash

Cold wash

Cycle time-45 min Total cycle time-270 min

Table 3 Details of yarn developed Yarn code

Fibres in blend

Proposed Actual blend ratio blend (Linen: Silk) ratio (Linen: Silk)

Yarn count (Lea/ Ne)

100% Linen

–

100:0

100:0

L:E 70:30

Linen/ Eri silk

70:30

L:E 50:50

Linen/ Eri silk

L:M 70:30

Twist (m−1 )

Yarn dia (micron)

Packing co-efficient

80.5/29 717.4

199

0.43

68:32

80/28.8 590.2

259

0.27

50:50

51:49

74.7/ 26.9

601.3

292

0.23

Linen/ Mulberry silk

70:30

71:29

80.4/ 28.9

547.8

229

0.34

L:M 50:50

Linen/ Mulberry silk

50:50

48:52

79.7/ 28.7

628

238

0.33

L:T 70:30

Linen/ Tasar silk

70:30

68:32

79.4/ 28.6

427.6

276

0.24

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Table 4 Fabric constructional parameters Fabric code

S/L

Warp yarn

Silk filature

Weft yarn

100% linen

Thread count

Thread density

Warp (Ne)

Weft (Ne)

EPI

PPI

156

29.0

116

91

Plain

94.3

0.224

Weave

Areal density (g/m2 )

Fabric thickness (mm)

S/LE 1

L:E 70:30

28.8

116

93

Plain

102.0

0.270

S/LE 2

L:E 50:50

26.9

118

90

Plain

106.1

0.293

S/LM 1

L:M 70:30

28.9

117

102

Plain

104.7

0.246

S/LM 2

L:M 50:50

28.7

116

99

Plain

113.6

0.262

S/LT 1

L:T 70:30

28.6

116

100

Plain

114.2

0.294

3. Tensile properties have been tested using TensoMaster (Single Yarn Strength Tester). 4. Whiteness Index was measured using Datacolor 600. Fabric Constructional Parameters. Developed fabrics have been subjected to washing and all the fabric samples were conditioned and tested in standard atmospheric conditions. The fabric constructional parameters evaluated were warp thread density (ends per inch—EPI) and weft thread density (picks per inch—PPI), fabric weight per unit area and fabric thickness. Warp and weft densities were measured according to the ASTM D3775-03 standard. Yarn linear density and fabric weight per unit area were determined according to the ASTM D1059 standard using an electronic weighing balance. The thickness of the fabrics was measured according to ASTM D1777-96 standard using a gauge-type thickness tester (Maker—Techno Instrument) at a pressure of 100 Pa. Fabric Stiffness. Fabric stiffness was tested using Prolific Stiffness Tester as per IS 6490:1971 test method by measuring the bending length. The bending length in the weft direction has been reported here. Drape Coefficient %. Drape testing is carried out as per IS 8357:1977 test method. The drape coefficient is calculated as the ratio of the projected area of the drape specimen to its theoretical maximum, as per the formula given below: Drape co − e f f icient % =

w W

w −a −a × 100 W × 100 A−a A−a

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where A is the area of the circle of 25 cm diameter, a is the area of the circle of 12.5 cm diameter, w is the mass of the drape pattern and W is the mass/area of ammonia paper, used for drape testing. Crease Recovery. Crease recovery properties of the fabric samples were determined by measuring the Crease recovery angle following IS 4681: 1981 standard using Crease Recovery Tester (Maker—Toyoseiki, Tokyo). Pilling Resistance. Resistance to pilling plays a very important role in determining the wearability of clothing. The pilling resistance of the linen and silk blended fabrics was tested using a paramount digital pilling tester following BS 5811:1986 standard. Abrasion Resistance. The abrasion resistance of the samples has been measured as per IS 12673–1989, using Prolific Abrasion Tester. Air Permeability. Air permeability of the fabric has been measured using TEXTEST FX 3300 air permeability tester at a pressure of 100 Pa; ASTM D737 has been followed. Water Vapour Permeability. Water vapour permeability through fabric samples was determined using Textest TF 165 Water vapour permeability tester, as per BS 7209 test standard. This tester measures the water vapour transmission rate based on the gravimetric method (dish method). The water vapour permeability of the fabric sample is calculated based on the following formula: WVP = (24 ∗ M)/(A ∗ T) g/m2 /24 h where M is the loss in mass (g); T, the time interval (h); and A, the internal area of the cup (m2 ). Absorbency Test. The test for absorptive capacity and sinking time has been conducted following the principles described in the ASTM D1117-18 test standard. Absorptive capacity provides a measure of the amount of liquid held within a test specimen after a specified time of immersion and drainage. Sinking time is the time required for the complete wetting of a specimen strip. The liquid absorptive capacity is calculated using the following formula. Water Absorbency % = (B − A)/A ∗ 100 where A = Specimen weight before immersion and B = Specimen weight after immersion. Wicking Test. This test has been conducted as per DIN 53,924 test standard using a vertical wicking tester. Fabric samples were cut along weft direction (20 cm × 5 cm) and mounted on a vertical wicking tester. The height reached by the wicking liquid along the fabric was noted for up to 30 min, at different time intervals. Dimensional Stability Test (Shrinkage). Fabric dimensional stability with respect to shrinkage test was conducted as per IS 3561: 1989 standard test method. For each variety of fabric, 5 replications were taken. Dimensional changes of specimens are

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calculated separately in each direction. The degree of shrinkage (expressed in %) was calculated using the following formula: Dimensional change, % = 100(b − a)/a where, a = mean original dimension before treatment for each test specimen. b = mean final dimension after treatment for each test specimen.

3 Results and Discussion 3.1 Yarn Properties The result of the blend ratio in the yarn has been given in Table 3. The tensile properties of the developed yarns have been given in Table 5. From the test results it has been observed that the tenacity of yarn has reduced with the increase in silk%, whereas the elongation % of yarn has been increased, resulting highest work of rupture for a 50:50 blend. It is known that a large difference in breaking elongation of the blending fibres adversely affects the blended yarn tenacity [5]. Thus, even though, linen and silk both have good tensile strength, due to the difference in elongation %, the tensile strength has been adversely affected. The same trend has been observed in a work done by Kemp and Owen [6], on cotton/nylon blend, it has been observed that specific stress at break reduces with the increase in nylon proportion till the mid-point and thereafter it again increases, whereas elongation at break increases with increase in nylon proportion throughout the range. In wet spinning, it was not possible to produce silk-rich samples, hence in this research analysing the complete range has not been possible. Yarn evenness, imperfection results and the whiteness index value have been given in Table 6. It has been observed that U% and CVm% are comparatively lower in linen: mulberry blends. There is a significant reduction in nep formation after blending with silk and with an increase in silk %, it has reduced. The quality of the tasar silk sliver was not good, because of thick/ thin places and more nep formation. The whiteness index was higher in the case of 100% linen yarn, followed by mulberry: linen, eri: linen and tasar: linen blend. It is due to the white colour of mulberry silk, off white colour of eri silk and the natural brown colour of tasar silk. The whiteness index reduces with an increase in silk proportion. SEM images of cross-sections of different blended yarns have been given in Fig. 3.

3.2 Fabric Properties The tactile comfort properties of the developed fabrics have been given in Table 7. As the developed yarns have been used in the weft direction, the crease recovery

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Table 5 Tensile properties of the developed yarns Yarn code

B-force (gf)

Elongation (%)

Tenacity (g/tex)

B-work (gf*cm)

100% Linen

446.6

2.1

21.6

210.1

L:E - 70:30

307.9

3.5

14.8

228.0

L:E - 50:50

292.4

4.7

13.1

350.4

L:M - 70:30

341.9

2.9

16.5

212.3

L:M - 50:50

355.9

3.3

17.0

269.4

L:T - 70:30

275.4

2.6

13.1

159.3

Table 6 Quality parameters of the developed yarns Yarn code

U%

CVm%

Thin 50% /km

Thick 50% /km

Neps 200% Total IP /km Stand. /km

Whiteness Index (CIE)

100% Linen

25.6

34.5

3942

2143

5401

11,485

50

L:E 70:30

25.0

32.8

3647

2030

3838

9514

25

L:E 50:50

25.3

32.8

4311

2023

3273

9607

19

L:M 70:30

23.8

31.4

2843

1767

3723

8332

25

L:M 50:50

23.0

30.1

2218

1354

2745

6317

18

L:T 70:30

26.3

34.7

4570

2225

4326

11,121

15

angle and the bending length of the samples have been reported here only for the weft direction. Crease recovery of the sample has been observed to be improved in the case of silk blends and bending length has been observed to be reduced for all types of silk blends, hence the stiffness has been reduced. The reduction is more with higher silk proportion. With this set of fabrics (silk in warp and linen and linen blend in the weft), no significant change has been observed for 70:30—linen: silk blends in the case of mulberry and eri silk. But good draping has been observed for 50:50—linen: silk blended yarn samples. Abrasion resistance of the fabrics in 50:50 blends and for S/LT1 have been seen as low. Pilling resistance has been observed good for all samples. Air permeability and moisture related properties of the fabrics have been given in Table 8. From the results it has been observed that fabric with 100% linen weft is having highest air permeability (as plotted in Fig. 4). With the incorporation of silk air permeability has reduced and the reduction is furthermore with an increase in silk portion. The reason can be attributed to the structure of these fibres. Linen fibres are polygonal in cross-section; whereas silk is having triangular cross-section and flat structure, it provides a better cover than linen, allowing less air to pass through.

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Fig. 3 Cross-sectional images of linen and linen-silk blended yarns

Table 7 Tactile comfort properties of developed fabrics Fabric code

Bending length, Weft (cm)

Crease recovery angle (Weft)

Drape co-efficient %

Pilling resistance (Avg. grading)

Abrasion resistance (No. of cycles)

S/L

4.07

53

49.5

4.8

5216.7

S/LE 1

3.80

55.2

52.5

4.8

5425.0

S/LE 2

3.26

57.7

46.7

4.9

4460.3

S/LM 1

3.56

59

51.4

4.9

5225.0

S/LM 2

2.99

65

42.6

4.5

4641.7

S/LT 1

3.28

65

46.4

4.9

3195.0

The diameter result (Table) shows that with similar yarn fineness value the diameter of silk blended yarns is more than 100% linen yarn, which reduces the inter-yarn spaces attributing to a better cover than 100% linen. It will keep the wearer warm in case of cold/windy conditions [2]. Water vapour permeability is a very important clothing comfort parameter, which determines the breathability of the fabric, i.e., the ability of the fabric to allow the insensible perspiration to pass from the skin to the atmosphere and make the wearer comfortable. For comfort, the permeability to water vapour of clothing fabric should be as high as possible, to allow for the escape of water vapour, which is constantly

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Table 8 Air permeability and moisture-related properties of the developed fabrics Fabric code

Air permeability (cm3 / cm2 /s)

S/L

Water vapour Wicking permeability height@ 10 min (cm)

Water Absorbency

Shrinkage %

Absorbency %

Warp

Weft

Sinking time (s)

94.5

1384

4.38

180.0

8.1

5.75

0

S/LE 1 85.3

1424

4.6

186.4

10.6

4.96

1.58

S/LE 2 57.4

1607

5.48

201.5

10.0

5.13

1.58

S/LM 1

86.4

1585

3.72

192.8

12.7

5

0.5

S/LM 2

37.6

1653

4

205.8

13.2

3.67

0.67

S/LT 1

56.4

1446

7.1

220.0

12.1

5

2

Fig. 4 Air permeability of linen and linen blended fabrics

being released from the skin [7]. Even though air permeability is less in the case of silk blends, very good water vapour permeability also has been observed in the silk blends as well, which can be attributed to high moisture regain of silk fibre compared to linen, which allows more moisture flow by absorption–desorption method [8, 9], even though the transmission by diffusion may be less. Low air permeability and high water vapour permeability would provide a comfortable feel to the wearer both in summer and winter conditions. Very good wicking and water absorbency has been observed for all samples. The highest wicking and water absorbency have been observed in tasar blended samples. Vertical wicking along the weft of the samples has been plotted in Fig. 5. Studying the dimensional changes to wash, it has been observed that shrinkage % was lowest in the fabric with 100% linen weft, followed by mulberry, eri and tasar blends. Considering all the tested parameters bending, crease recovery, drape, air permeability, abrasion, and shrinkage value it is concluded that the linen-mulberry 50:50 blend will be most suitable from the fabric comfort viewpoint, to be used as a dress in winter.

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Fig. 5 Vertical wicking of fabrics along the weft

4 Conclusions The present study deciphers that linen silk blended yarn can be successfully produced in a wet flax spinning system. Blending silk with linen will offer a niche product with improved properties, better dimensional stability, better draping and crease recovery properties, and better protection in winter conditions without hampering breathability. Acknowledgements The authors acknowledge Central Silk Board, Govt. of India, Bangalore for funding this project work. Authors appreciate the support received from Raymonds, Amravati, India in developing yarn samples and acknowledge the help and support received from Dr. Subhas V. Naik, Ex-Director, CSTRI, CSB, Bangalore in conceptualization and co-ordination of this research work.

References 1. 2. 3. 4. 5. 6. 7. 8. 9.

Adnan M, Moses J (2020) Revista Matéria 25 Das B, Padaki NV, Jaganathan K, Ashoka HM (2021) Jr Inst Engg (India): Series E 102:145–154 Behera BK, Mishra R (2007) Ind Jr Fibre Text Res 32:72–79 Behera BK (2007) Autex Res Jr 7:33–47 http://mytextilenotes.blogspot.com/2009/04/blending-2.html?m=1 Kemp A, Owen JD (1955) Jr Text Inst Transc 51, T 684-T698 Kothari VK (2000) Quality control. Indian Inst of Tech, Delhi, India, pp 276–294 Adamu BF, Gao J (2022) Fashion & textiles. Springer Open 9:1–10 Das B, Das A, Kothari VK, Fangueir R, Araujo M (2009) Jr Engg Fib and Fab 4(4):20–28

Study of Sisal Nonwoven Mulching for Watermelon Cultivation and Its Effect on Soil Nutrition Values Janki R. Patel, Tasnim N. Shaikh, and Bharat H. Patel

Abstract In this research work an attempt has been made to prepare a nonwoven fabric using a sustainable natural fibre ‘Sisal’ and to use the same for the mulching purpose for the cultivation of watermelon. The sisal fibre nonwoven was prepared by needle punching technique with three different GSM values, i.e., 300, 600, and 900. The result is further contrasted against the synthetic mulch using plastic. The study explores the soil characteristic in terms of its macronutrient (organic carbon, phosphorous, potash, and sulfur) and micronutrients (zinc, iron, manganese, copper) as an effect of the mulching. The watermelon cultivation cycle with the mulching takes 65–70 days. The process of cultivation was maintained identically for all the chosen mulches. The nonwoven was characterised by its thickness and permeability characteristics. The results showed a promising use of the sisal fibre nonwoven mulch for the cultivation of watermelon. Sisal fibre nonwoven mulch of 300 and 600 GSM yielded a normal result while the 900 GSM value yielded abnormal values. Keywords Sisal fibre · Needle punching · Mulch · Watermelon crop · Soil nutrition

1 Introduction “Mulch” is an English word derived from the original German word “molsch,” which means soft or beginning to deteriorate, whereas the word mulching means covering, protecting, insulating, and so on [1, 2]. Mulching is classified into two types: organic and inorganic. Organic mulches are those that are derived from nature, such as animal waste (manure, stubbles) or agricultural waste (maize stalks, jowar stalks, etc.). Aside J. R. Patel (B) · T. N. Shaikh · B. H. Patel Department of Textile Engineering, Faculty of Technology & Engineering, The Maharaja Sayajirao University of Baroda, Kalabhavan, Rajmahal Road, Baroda 390001, India e-mail: [email protected]; [email protected] B. H. Patel Department of Textile Chemistry, Faculty of Technology & Engineering, The Maharaja Sayajirao University of Baroda, Kalabhavan, Rajmahal Road, Baroda 390001, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024 D. Gupta et al. (eds.), Functional Textiles and Clothing 2023, Springer Proceedings in Materials 42, https://doi.org/10.1007/978-981-99-9983-5_19

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from these, traditional components such as bark, grass clippings, wood chips, dry leaves, paper, and so on are also included in this category [3, 4]. Essentially, they conceal the characteristics of previously living materials. While inorganic mulches are composed of petroleum-based synthetic polymeric sheets, commercially available materials include Linear Low-Density Polyethylene (LLDPE), Ethylene Butyl Acrylate (EBA), Low-density Polyethylene (LDPE), and Ethylene Vinyl Acetate (EVA). They are either camouflaged or contrasted with crop colours, but a popularly used economical one in India is a black polyethylene sheet [2–4]. Currently, experiments with biodegradable polymers are being conducted to control soil contamination caused by these synthetic but non-biodegradable materials [4]. Organic mulches and biodegradable plastic mulches eventually decompose and add nutrients to the soil surface, improving moisture retention capacity and increasing the humus layer. However, whether or not these beneficial effects are earned, and to what extent, they are influenced solely by the type of mulch, soil characteristics, and climatic conditions. For example, wood chips, straw, green manures, and bark mulches have been found to deliver more nutrients than inorganic mulches. However, despite their higher nutrient supply capability, their extensive use in agricultural lands can harm sensitive crops, living organisms, and water resources [3]. The present work deals with the development of a needle-punched nonwoven mulch fabric from sisal fibres. They were used for a watermelon cultivation cycle of 65–70 days to study their effect on soil nutrition values as well as their impact on living organisms and water conservation capabilities.

2 Materials and Methods 2.1 Materials The sisal fibres were procured from the Sisal Research Station, Odisha. A plastic mulch made of polypropylene (PP) with a 80 GSM used by the farmers was taken as a commercial variant in the study (see Fig. 1).

2.2 Methods Mulch Preparation and Laying. The needle-punched nonwoven fabrics; 300 GSM, 600 GSM, and 900 GSM were prepared from sisal fibres using the DILO laboratory model machine at ICAR- NINFET, Kolkata, West Bengal. The prepared needlepunched nonwoven mulches were laid in parallel with a commercial plastic sheet for the selected watermelon crop as per the ridged pattern [5].

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Fig. 1 Materials of mulch

2.3 Testing Fibre and Fabric Testing. Standard test methods (see Table 1) were used to evaluate the characteristics of constituent fibres and mulch fabrics after due conditioning them for 24 h at 27 ± 2 °C & 65 ± 2% RH [6]. Soil Testing. The required soil samples were collected manually before laying the mulches and after the completion of the crop cycle. The collection was done in a zig-zag pattern to prepare an unbiased random soil sample to study the effect of mulching [7]. Soil temperature and pH were measured using a thermometer and soil pH meter respectively [8]. The gravimetric method was used to measure the soil moisture [9]. The electrical conductivity (EC) of the soil was determined by measuring the electrical resistance of soil: water suspension made in 1:5 proportion with the help of a conductivity meter [10]. The macro and micro soil nutrition values were measured with Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) [11].

3 Results and Discussion 3.1 Fibre Parameters Test results for the fibre physical parameters are reported in Table 2 and they endorsed the presence of inherent higher variations in the selected natural fibres. These deviations in fibre values have also caused higher strength CV% of the selected natural fibres.

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Table 1 Fibre and fabric test methods Fibre properties

Test setup

Length

Manually measured using the scale for randomly selected 1000 fibres

Fineness

Cutting and Weighing ASTM D 1577 (1990)

Tensile strength

Lloyd Tensile tester (LRX model), ASTM D 5035 Gauge length = 100 mm, cross head speed = 100 mm/min, Load capacity = 2500 N

Fabric properties Physical properties Thickness

Mitutoyo thickness tester (Japan), IS 15891 (Part 2)

Grams per square meter

Sample size = 100 mm × 100 mm, electronic weighing balance with 0.01 gm accuracy, IS 15891 (Part 1)

Mechanical properties Tensile strength

Lloyd tensile tester (LRX model), ASTM D 5035 Gauge length = 100 mm, Cross head speed = 100 mm/min and Sample size = 200 mm × 25.4 mm

Tear strength

Trapezoidal tear strength on Lloyd tensile tester, ISO 9073–4: 1997 Sample size = 150 mm × 100 mm, Cross head speed = 300 mm/min

Functional properties Air permeability

METEFEM air permeability tester, at 10 Pa pressure, ASTM D 737

Water vapour permeability

Evaporative dish method, BS 7209

Light transmission

UV-2000F, AATCC TM 183–2000

Table 2 Fibre test results

Properties

Average

CV%

Length (mm)

1041.0

10.80

351.9

14.72

48.6

16.94

Denier Tensile strength (gpt) *

gpt = gram per tex

3.2 Mulch Fabric Characteristics The physical and mechanical mulch fabric parameters measured are given in Table 3. All the natural fibre-based mulches are thicker as well as heavier than ongoing plastic mulch as expected. Higher tear strength and tensile strength values of the stronger sisal fibre-based mulches are observed in comparison to the competitor’s plastic mulch [Tables (2 and 3)], substantiating their better sustainability against hostile environment conditions as well as animal foot pass. Both the mechanical parameters

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have shown a rise with the increased fabric GSM, likely due to the increased number of fibres sharing the applied load. However, the increase didn’t reciprocate in the same proportion as the rise in GSM. This behaviour may be attributed to the differential extent of binding occurring amongst the constituent fibres on needle punching. Test results for the functional characteristics are summarised in Table 4. All natural mulches, regardless of size, are found to be breathable compared to plastic sheets. Hence, this ease of air transmission has given a positive trace on the soil and helped in preventing algae formation below the natural mulches. Additionally, this has created a better hibernation environment for the earthworms; these silent helpers facilitate making soil further fertile with due softness. The poor air transmission in association with the deposition of condensed water vapours beneath the plastic mulch invariably led to algae formation. Unlike the plastic mulch, the water vapour transmission rate for the natural mulches was affected by the surrounding environment’s temperature. However, the plastic mulch didn’t show an increase in water vapour transmission at higher temperatures, but the risen water, on getting heated, was found deposited underneath the Table 3 Physical and mechanical properties of mulch fabrics Sample code

S1

S2

S3

S4

4.2

5.8

7.9

0.05

310

610

918

80

Physical properties Thickness (mm) GSM

(g/m2 )

Mechanical properties Tensile strength (N/mm2 ) 0.0289 x 0.0384 0.277 × 0.1409 0.375 × 0.351 0.0001 × 0.0001 [MDxCD] Tearing strength (N) [MDxCD] *

17 × 18

82 × 85

133 × 142

5×5

S1 = 300GSM, S2 = 600 GSM, S3 = 900 GSM, S4 = Plastic

Table 4 Functional properties of mulch fabrics Air permeability (m3 /m2 /hr) Water vapour permeability

S1

S2

S3

S4

2300

2500

2600

0

(g/m2 /Day)

Standard Temp (27 °C)

301.38

301.38

301.38

301.38

Atmospheric Temp (42 °C)

904.16

602.77

602.77

301.38

40

> 50

> 50

47

Above the mulch

42.5°c

42.5°c

42.5°c

42.5°c

Below the mulch

29.5°c

29.5°c

29.5°c

29.5°c

Light transmission UPF Values Soil temperature (°c)

*

S1 = 300 GSM, S2 = 600 GSM, S3 = 900 GSM, S4 = Plastic

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Table 5 Watermelon yield Sample code

Yield (in kg/Plant/season)

Average diameter (in cm)

Average length (in cm)

S1

16.5

54.88

26.50

S2

16.5

52.20

29.11

S3

16.3

51.00

24.44

S4

16.5

53.55

26.87

*

S 1 = 300 GSM, S 2 = 600 GSM, S 3 = 900 GSM, S 4 = Plastic

plastic in condensed water droplets, returning to the dish. The rise in water vapour transmission rate was almost doubled with low 300 GSM sisal mulch in the group at higher temperatures. This behaviour is mainly attributed to the lower coverage provided by the low GSM fabric. Here, higher temperatures represent the average field temperature noted during the daytime for the crop cycle. The UPF values recorded for all the sisal-based mulches and plastic mulch fall within the preferable range of 40–50, witnessing excellent resistance to sunlight according to AS/NZS 4399 Standard. It can be observed that the soil temperature below the mulch remained the same and on the lower side irrespective of mulch type and size. This was due to water vaporisation followed by its condensation, the same cycle observed in the case of hydrophobic plastic mulch, which has also completely covered the soil. Whereas the hygroscopic but breathable sisal fibre mulches have proven their equal thermal insulation potential via an evaporative cooling mechanism. However, this was attained at the cost of two to three times more water vapour loss. Nevertheless, this water loss has invited the breeding of soil-friendly earthworms and resisted algae development, which is harmful to the soil.

3.3 Watermelon Yield Crop yield results have demonstrated that sisal fibre-based mulches are equally potent as commercial plastic-based mulch in watermelon yield as well as quality (see Table 5).

3.4 Soil Characteristics Moisture, pH, and electrical conductivity of the soil were measured just before laying the mulches, viz., on getting the field prepared after ploughing as well as on completion of the crop cycle. Test values are given in Table 6. The soil was found to have moisture at the end of the crop cycle with all the categories of mulches in comparison to the prepared barren land soil before laying seeds. Hence, the soil moisture observed was identical to plastic mulch for 600

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Table 6 Soil Characteristics Before laying mulch

After completion of the crop cycle S1

S2

S3

S4

Standards

Soil moisture (%)

0.17

18.54

26.53

26.63

26.85

-

Soil pH

6.97

7.21

7.21

7.27

7.93

6.5 to 8.2 normal

Electric conductivity (mS/m) 1:2

74

116

116

160

87

< 100 normal 100–200 more soluble alkali

S 1 = 300 GSM, S 2 = 600 GSM, S 3 = 900 GSM, S 4 = Plastic * mS/m = milliSiemens/meter *

GSM & 900 GSM sisal mulches but about thirty per cent lower for 300 GSM sisal mulch. This behaviour is mainly due to regular watering cycles followed as well as the water retention capacities of the mulches. Soil pH is important for plant growth because it decides the presence of nutrients. The soil with a pH of 6.5 is highly nutrient for plant growth [12]. Generally, its shift above seven indicates alkalinity and soil acidity if reduced than seven. A small rise in soil pH values was noted invariably for all the mulches used during the study after the crop cycle. However, the measured pH values are well within the normal pH range prescribed, viz., 6.5 to 8.2, and endorse their plant friendliness. The EC level of the soil witnesses how much soluble salt is flushed out of the soil. Too-low a value points towards a higher quantum of nutrient loss, and vice versa [13]. In the present study, the EC level for the soil samples collected below all the sisal mulches has shown a marginal increase from the initial state. This rise has indicated the presence of more soluble alkalis. On the contrary, the loss of nutrients with the plastic is higher but still well within the normal range.

3.5 Macro Soil Nutrients Test Results Macronutrients are essential for plant growth and a good overall state of the plant. The primary macronutrients are nitrogen (N), phosphorus (P), and potassium (K). The soil supply of N, P, K, and S is often supplemented by fertiliser and manure. Nitrogen (N) is essential for plant development because it is involved in energy metabolism and protein synthesis. The plant absorbs nitrogen in the form of nitrate. This macronutrient has a direct relationship with plant growth. It is required for photosynthesis activity and the formation of chlorophyll. Nitrogen is primarily involved in the aerial zone, the visible part of the plant. It encourages cellular growth. A lack of nitrogen causes a loss of vigour and colour. Phosphorus (P) promotes root growth. It favours flowering in the aerial zone. Although phosphorus is required during the plant’s growth period, it plays a much larger role during the flowering

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stage. Phosphorus is involved in the transport and storage of energy. It improves the plant’s overall health and ability to withstand adverse climatological conditions. Phosphorus is required for the formation of organic compounds as well as the proper execution of photosynthesis. A lack of phosphorus causes late, deficient flowering, browning and wrinkling of the leaves and a general lack of vigour. Potassium (K) is involved in the regulation of water and the transport of the plant’s reserve substances. It increases photosynthesis capacity, strengthens cell tissue, and activates the absorption of nitrates. Potassium stimulates flowering and the synthesis of carbohydrates and enzymes. This, in turn, provides an increase in the plant’s ability to withstand unfavourable environments such as low temperatures and prevents withering. Therefore, a lack of potassium reduces plant resilience to dry spells and frosts or to a fungus attack. This, in turn, results in a lack of balance among other nutrients, such as calcium, magnesium, and nitrogen. When there is a potassium insufficiency, dark spots appear on the leaves. Sulfur (S) participates in the formation of chlorophyll. It is necessary for performing photosynthesis and intervenes in protein synthesis and tissue formation. Sulfur is fundamental in the metabolising of nitrogen since it improves nitrogen efficiency. Sulfur also improves plant defences in general. A shortage of sulfur is rare, but when it does occur, the plant becomes lighter in colour, taking on a pale green appearance. General chlorosis is seen, like what occurs with a nitrogen deficiency [14, 15 and 16]. Macro soil nutrient values measured for the soil collected before and after the watermelon crop cycle (65–70 days) are summarised in Table 7. It should be noted that during the crop cultivation process, water-soluble fertilisers were given at regular intervals of 4 days. This cycle was initiated after 10 days of sowing or laying mulch through usual drip irrigation. Fertilisers used in the course were IFFCO, GSFC products NPK 19.19.19, MKP 0.52.34, NPK 13.40.13, calcium nitrate, boron, and NK 13.00.45 in the ratio of 12.5 kg/hectare as well as micronutrients and gibberellic acid in 2 L/hectare. They include nutrients like Nitrogen, Potassium, Boron, Calcium Nitrate, and Gibberellic acid (GA) to enhance flowering and fruit development and reduce the incidence and/or severity of some physiological disorders that occur due to environmental conditions. This has resulted in increased soil nutrient levels after a crop cycle. Table 7 Macro soil nutrients value Nutrients

Before laying mulch

After completion of the crop cycle S1

S2

S3

S4

Organic carbon (%)

1.38

1.38

1.38

1.38

0.64

Phosphorous (Kg/Ac)

10

11

11

9

7

Potash (Kg/Ac)

80

38

38

202

28

Sulfur (Kg/Ac)

8.40

9.80

9.80

12.80

7.8

S 1 = 300GSM, S 2 = 600 GSM, S 3 = 900 GSM, S 4 = Plastic * kg/Ac = Kilogram/Acre *

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It can be observed that newly designed mulch has either facilitated in preserving macronutrients except for potash (K). However, sample S3 made with the highest 900 GSM has behaved differently in the group and showed abruptly high potash and sulfur values; this needs further investigation. Further plastic mulch lags natural fibre mulches in preserving or adding to essential macronutrient molecules. There was no change observed in organic carbon (%) for the soil samples collected beneath the sisal mulches but the value became almost half for the soil obtained underneath the plastic mulch. Further, improvement in the phosphorous (P) values was noted for 300 and 600 GSM mulches but an undesirable drop with 900 GSM as well as plastic mulch. This differential behaviour of 900 GSM was continued for potash and sulfur, which need to be investigated for multiple trials before concluding. In general, all the macro soil nutrient values were reduced in the case of polypropylene mulch. Thus, Sisal mulches have shown their superiority over competitor plastic-based mulch in terms of their ability to preserve macro nutrition values in the present study. This behaviour substantiates observations made for soil pH and EC values (see Table 6).

3.6 Results from Micro Soil Nutrients Test Micro soil nutrient values are given in Table 8. Zinc (Zn) is an important plant regulator essential in root and plant growth. Iron (Fe) is required for the formation of chlorophyll in plants. Manganese (Mn) assists iron in chlorophyll formation. It also serves as an activator for enzymes in the growth process. Copper (Cu) activates enzymes and catalyses reactions in several plant-growth processes. The presence of copper is closely linked to Vitamin A production and helps ensure successful protein synthesis. Zinc (Zn) is an important plant regulator, and essential in root and plant growth [15, 16]. It can be observed that zinc and manganese values have increased with all the sisal fibre-based mulch compared to barren land soil. But the reduction in copper was noticed with 300 GSM & 600 GSM mulches and conversely increased for 900 GSM. The iron value has shown an increment for 300 GSM & 600 GSM, but a reduction for 900 GSM. However, plastic mulch has shown a favourable rise in iron Table 8 Micro soil nutrients value (ppm) Nutrients

Before laying mulch

After completion of the crop cycle S1

S2

S3

S4

Zinc (Zn)

0.13

0.17

0.17

0.18

0.12

Iron (Fe)

2.33

2.38

2.38

2.25

2.99

Manganese (Mn)

2.27

2.65

2.65

3.24

3.16

Copper (Cu)

0.88

0.56

1.03

1.03

0.69

S 1 = 300 GSM, S 2 = 600 GSM, S 3 = 900 GSM, S 4 = Plastic * ppm = parts per million *

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and manganese values of the soil along with an undesirable drop in zinc and copper. Thus, in aggregate sisal mulch has shown better support in retaining soil nutrients than plastic mulch in the present observation.

4 Conclusion The regular addition of water-soluble fertilisers through drip irrigation systems adopted during the crop cycle has resulted in the enhancement of micro and macro soil nutrient value. Better macro soil nutrition values, especially for phosphorus and sulfur, have been observed for the soil collected on the completion of the crop cycle beneath the sisal fibre mulches invariably, advocating their good retention potential. But all the macronutrient values of the soil were reduced beneath the plastic mulch. The breathable sisal fibre-based mulches were found to be more soil-friendly with their better moisture retention capacity, pH, and EC values, and also supported the breeding of soil-friendly earthworms. The plastic mulch due to its zero-air permeability not only failed in providing a breeding environment to the earthworm but rather invited fungus formation on the accumulation of condensed water vapours at many points. These green mulches have also exhibited equivalent potential in terms of watermelon yield as well as quality. A further in-depth study can explore new ecological ways for mulching in the agro-textile sector.

References 1. Iqbal R, Raza MAS, Valipour M, Saleem MF, Zaheer MS, Ahmad S, Toleikiene M, Haider I, Aslam MU, Nazar MA (2020) Potential agricultural and environmental benefits of mulches—a review. Bull Natl Res Centre 44(1):1–16 2. Jacks CV, Brind WD, Smith R (1955) Mulching technology comm., no. 49, commonwealth. Bull Soil Sci 118 3. Singh SB, Pramod K, Prasad KG, Kumar P (1991) Response of Eucalyptus to organic manure mulch and fertiliser sources of nitrogen and phosphorus. Van Vigyan 29(4):200–207 4. Kasirajan S, Ngouajio M (2012) Polyethylene and biodegradable mulches for agricultural applications: a review. Agron Sustain Dev 32:501–529 5. Kader MA, Senge M, Mojid MA, Ito K (2017) Recent advances in mulching materials and methods for modifying soil environment. Soil Tillage Res 168:155–166 6. Booth JE (1996) Principle of textile testing, 3rd edn. CBS Publishers & Distributors Pvt, Ltd 7. Ackerson JP (2018) Soil sampling guidelines. Purdue University, Purdue Extension 8. Nicholas P (ed) (2004) Soil, irrigation and nutrition (No. 2). South Australian Research and Development Institute 9. Reynolds SG (1970) The gravimetric method of soil moisture determination Part I a study of equipment, and methodological problems. J Hydrol 11(3):258–273 10. Rayment GE, Higginson FR (1992) Australian laboratory handbook of soil and water chemical methods. Inkata Press Pty Ltd. 11. General Instrumentation https://www.ru.nl/science/gi/facilities-activities/elemental-analysis/ icp-oes/. Accessed on 02 Jan 2023

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12. Mosaic crop Nutrition https://www.cropnutrition.com/nutrient-management/soil-ph. Accessed on 02 Jan 2023 13. USDA Natural Resources Conservation Service https://www.nrcs.usda.gov/sites/default/files/ 202210/Soil%20Electrical%20Conductivity.pdf. Accessed on 02 Jan 2023 14. Chalker-Scott L (2007) Impact of mulches on landscape plants and the environment—a review. J Environ Hortic 25(4):239–249 15. Zewide I, Sherefu A (2021) review paper on effect of micronutrients for crop production. J Nutr Food Proc 4(7)

Development of Cost-Effective, Eco-Friendly Sanitary Pads for Better Health and Sanitation of Rural Women R. Niveda and G. Ramakrishnan

Abstract One of the major challenges India is facing is the plastic waste generated by commercial sanitary pads. One sanitary pad equals 4 plastic bags. It affects the water bodies, and plastic pads do not degrade for years together. More than 80% of sanitary pad users are not satisfied with the existing pads as they cause a lot of health issues because of the chemicals and plastics in them. This project deals with the development and characterisation of a biodegradable sanitary pad (Bio-pad) that is an alternative to commercial plastic pads. A sanitary napkin consists of three layersThe top, bottom layer, and the absorbent core. Viscose, bamboo spun lace nonwovens were chosen for the top layer. Wood pulp, kenaf, banana, and flax fibres were chosen for the absorbent core because of their good absorbency and antimicrobial properties. Bioplastics made of corn starch, and tapioca starch were chosen for the bottom layer of the napkin. All the materials were characterized and analyzed as per standards. The best material for each layer was selected to be made into a biodegradable sanitary pad. The produced sanitary napkin was tested as per BIS standards and compared with commercial sanitary napkins. It was found to perform as well as commercial sanitary pads. Keywords Biodegradable materials · Characterization · Sanitary napkin · Testing · Sustainability

1 Introduction Natural fibres are available in abundance throughout the world but are not properly utilized. Some of the natural fibres include kenaf, jute, hemp, banana, bamboo, cotton, flax, water hyacinth, coir, etc. [1]. These fibres are completely degradable, R. Niveda (B) · G. Ramakrishnan Department of Fashion Technology, Kumaraguru College of Technology, Coimbatore, Tamilnadu, India e-mail: [email protected] G. Ramakrishnan e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024 D. Gupta et al. (eds.), Functional Textiles and Clothing 2023, Springer Proceedings in Materials 42, https://doi.org/10.1007/978-981-99-9983-5_20

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renewable, and eco-friendly. The issue of non-biodegradability of personal hygiene products is a serious threat all over the world. The naturally available absorbent fibres such as organic cotton, banana fibre, jute, bamboo, etc., are widely available and biodegradable in nature having a low carbon footprint which not only makes it eco-friendly but also reduces the cost of sanitary pads [2]. A sanitary napkin usually contains 3 layers, the top layer, the absorbent core, and the bottom layer. In this study, materials suitable for all three layers were sourced or manufactured. The materials are tested as per standards and the best resulting material was made into a sanitary pad that was tested as per BIS standards and compared with a commercial pad.

2 Materials and Methods 2.1 Materials Viscose, bamboo spun lace nonwovens were chosen for the top layer of the sanitary pad. Wood pulp, kenaf, banana, and flax fibres were chosen for the absorbent core because of their good absorbency and antimicrobial properties. Bioplastics made of corn starch, and tapioca starch were chosen for the bottom layer of the napkin.

2.2 Methods Sourcing of Materials. Viscose, bamboo spun lace nonwovens, wood pulp, kenaf fibre, banana, flax fibres, and bioplastics made of corn starch, and tapioca starch were sourced from Go Green Pvt Limited. The top layer of viscose and bamboo was sourced as spunlaced nonwovens of 40 gsm. Corn starch and tapioca starchbased bioplastics were sourced as sheets with a width of 80 mm and 40gsm. Raw fibres (banana, flax, kenaf) of staple length were chosen for the absorbent core, which underwent pulping to be used in sanitary pads. Wood pulp was sourced as ready-made pulp which did not undergo a pulping process. Pulping of the Absorbent Core. The fibres chosen for the study were kenaf, banana, flax and wood pulp. Kenaf, banana and flax fibres were extracted from the stem of their respective plants. These fibres were pulped in order to be used as an absorbent core in the sanitary napkin. Kenaf fibres were boiled in a container having water and wood ash for nearly 7 h. These fibres were removed from the container, washed, and pulped using a Hollander beater for an hour. The pulped fibres were removed from the beater and allowed to dry in the sunlight. Banana fibres were boiled in a container having water and wood ash for nearly 3 h. These fibres were then removed from the container, washed and pulped using a

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Hollander beater for an hour. The pulped fibres were removed from the beater and allowed to dry in the sunlight. Flax fibres were boiled in a container having water and wood ash for nearly 5 h. These fibres were then removed from the container, washed and pulped using a Hollander beater for an hour. The pulped fibres were removed from the beater and allowed to dry in sunlight. All the materials were taken for testing as per sanitary napkin standards. Material Testing for The Top Layer. The viscose and bamboo spun lace nonwovens were tested for top layer characterization. The top layer non-woven was characterized for moisture management test as per AATCC 195:2012. The tests include wetting time in secs, Absorption rate %/sec, maximum wetted radius in mm, spreading speed mm/sec, one-way transport index %, and overall moisture management capability. Both the viscose and Bamboo spun lace nonwoven were tested for above mentioned tests. The samples were tested at R.H 65% ± 2% and temp 21˚C ± 1˚C. Material Testing for Absorbent Core. Kenaf, flax, banana and wood pulp were tested for core layer characterization as per ISO ISO 17190–7/WSP 240.3. The test includes free swell absorptive capacity using artificial blood. Material Testing for Bottom Layer. The bioplastics sourced from green plastics and Plasto manufacturing company were tested for bottom layer characterization. The tests for bottom layer characterization include moisture vapour transmission rate and liquid resistance. Moisture vapour transmission (breathability) was tested as per ASTM E 96–95 at 32 °C with humidity in the chamber being 50 ± 2%. Liquid resistance–Hydrohead was tested as per AATCC 127:2014 at a rate of rising 600 mm wc/min. Sanitary Napkin Making. A sanitary napkin was produced with the optimized materials for top, bottom and core layers. The optimized top layer, core layer and bottom layer were selected and sandwiched using a miniature sanitary napkin machine to be made into a sanitary napkin. Sanitary Napkin Testing. The produced sanitary napkins were tested as per BIS Standards. The tests include length, width, thickness, absorbency, pH and biodegradability as per IS5405:1980. The sample was tested at: R.H.65% ± 2% and Temp. 21 °C ± 1 °C.

3 Results and Discussion Top Layer Characterization. The viscose and bamboo spun lace nonwovens were tested for overall moisture management capability. Wetting time and one-way transport index was better in viscose than in bamboo. The absorption rate, maximum wetted radius, spreading speed and overall moisture management capability were better in bamboo than in viscose. The test was taken as per the standard AATCC 195:

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2012. Viscose, bamboo spun lace nonwovens were chosen for the top layer. Wood pulp, kenaf, banana, and flax fibres were chosen for the absorbent core because of their good absorbency and antimicrobial properties. Table 1 indicates the top layer characterisation where the overall moisture management is excellent if the grades are above 0.8. Both viscose and bamboo show excellent moisture management capability. Bottom Layer Characterization. Both enzymatic bioplastics and starch-based bioplastics were chosen for the study. From the results obtained in Table 2, it is clear that enzymatic bioplastics were better than starch-based bioplastics both in terms of moisture vapour transmission rate and liquid resistance. Moisture vapour transmission rate was tested as per ASTM E- 96–95 and liquid resistance was tested as per AATCC 127:2014. Absorbent Core Characterization. The pulped fibres were tested for free swell absorptive capacity. This test is taken to find the absorptive capacity of the material. Samples were tested at R.H.65 ± 2% and at temperature 21 °C ± 1 °C. This test was carried out with synthetic blood instead of saline solution. Figure 1 indicates that the Table 1 Top layer characterization Moisture management test AATCC 195: 2012 R.H.65% ± 2% AND TEMP. 21 °C ± 1 °C 100% viscose spun lace nonwovens

100% bamboo spun lace nonwoven

Top layer Bottom layer Top layer Bottom layer Wetting time in seconds

2.4152

2.3962

1.9094

1.8348

Absorption rate %/Sec

32.6653

54.1519

35.6769

62.9008

Maximum wetted radius in Mm

27

28

30

30

Spreading speed Mm/Sec

6.6755

6.7275

9.0103

9.013

Oneway transport Index %

355.8891

355.8891

352.1612

352.1612

0.8131

0.8438

0.8438

Overall moisture management capability 0.8131

Table 2 Bottom layer characterization Tests

Conditions

Tapioca Bioplastic

Corn Bioplastic

Moisture vapour transmission rate (Breathability) Astm E-96–95 G/M2/24 h

Temp 32˚C Humidity in Chamber 50 ± %

551.84

0

Water resistance—hydrohead test Aatcc 127: 2014 Mm water column

Rate of rising 600 mm Wc/ min

3030

267

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Fig. 1 Absorbent core characteristics

Table 3 Comparison between developed and commercial sanitary napkins Parameter

Biodegradable

Commercial

Length in mm

240

240

Width in mm

70

70

Thickness in mm

15

13

Absorbency and ability to withstand pressure under absorption( IS5405:1980)

Pass

Pass

Disposability( IS5405:1980)

Pass

Pass

pH Value (IS 1390:1961)

7.60

6.2

free swell absorptive capacity of wood pulp was higher followed by Kenaf, banana and flax in the units of g/g. Biodegradable Sanitary napkin versus Commercial sanitary napkin. The produced sanitary napkin was tested as per BIS standards and was also compared with the commercial sanitary napkin. The results revealed that both the samples passed all the tests as per BIS standards. Table 3 indicates that the biodegradable sanitary napkin produced was on par with commercial sanitary napkins in terms of quality. The biodegradable napkin was better than the commercial sanitary napkin in terms of sustainability and women’s personal hygiene.

4 Conclusion Wetting time and one-way transport index were better in viscose than in Bamboo. The absorption rate, maximum wetted radius, spreading speed and overall moisture management capability were better in bamboo than in viscose. Tapioca bioplastics were better than starch-based bioplastics both in terms of moisture vapour transmission rate and liquid resistance. The free swell absorptive capacity in g/g of wood pulp was higher than kenaf, banana and flax fibres. The biodegradable sanitary napkin produced was on par with commercial sanitary napkins in terms of performance.

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References 1. 2006 Song KH, Obendorf SK (2006) Chemical and biological retting of kenaf fibers. Text Res J 76:751–756 2. Barman A, Katkar PM, Asagekar SD (2017) Natural and sustainable raw materials for Sanitary Napkin. J Text Sci Eng 07

Decoding the Science Behind the Chemical Recycling of Textiles Sweta Singh and Prabir Jana

Abstract Recycling is one of the many ways sustainability can be achieved in textile and apparel industry. However, access to commercial technology is one of the several barriers toward fibre-to-fibre recycling. This paper tries to explore the supply chain and technology challenges of chemical recycling. This study scours the secondary sources of information from journals, websites, patent databases and blogs to track and document all the organizations associated directly and indirectly with the textile recycling domain. It was found that unlike a linear network the organizations are arranged in concentric circles. The upstream players like manufacturers (who convert waste textile to virgin textile) comprise only 25% and concentrated in the inner circle and enjoy least visibility. The think tanks, industry associations, certification bodies, research foundations, marketers, brands, etc., are spread across the outer circle and enjoy the maximum visibility. The marketers, contract manufacturers and aggregators maintain the crucial links between the outer and inner circle. The patent analysis shows European (50%) and US organizations (40%) dominate the technology development and most of the patents will be available for commercialization after 2030–2035, thereby limiting the spread and adoption of technology worldwide. The chemical technologies mainly used for recycling are depolymerization and hydrolysis and the chemicals used for recycling are mostly ionic liquids or organic compounds. 80% of the patents are found to be new-age companies with an average age of 11 years without any history of textile machinery or chemistry. Keywords Chemical recycling · Cellulose dissolution · Polyester dissolution · Patented technology

S. Singh (B) · P. Jana Department of Fashion Technology, National Institute of Fashion Technology, Hauz Khas, New Delhi, India e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024 D. Gupta et al. (eds.), Functional Textiles and Clothing 2023, Springer Proceedings in Materials 42, https://doi.org/10.1007/978-981-99-9983-5_21

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1 Introduction There is a lot of textile waste as a result of the increasing global consumption of garments and other textiles. However, there aren’t many profitable recycling methods for textiles. Textile recycling from fibre to fibre has not been done extensively. The development of recycling technology is one of the main obstacles to achieving chemical recycling of textiles because the second-hand textile collection is highly developed [1]. Creating procedures to turn old textiles into raw materials for the production of new textile fibres is a significant challenge for the textile industry. This paper will be contributing to chemical recycling technologies. Textiles can be recycled from fibre-to-fibre chemically or mechanically. The mechanical method has traditionally been used to de-fibre fabrics into fibres, which can then be spun into recycled yarn and textiles with or without the addition of virgin fibres. For wool and cashmere, mechanical recycling can be accomplished with good results, but for the majority of other fibres, mechanical recycling results in recycled fibres of lower quality. Because of this, mechanical recycling is frequently referred to as down-cycling [2]. Despite the lack of large-scale chemical textile recycling efforts, numerous smaller-scale initiatives including Eco Circle (Teijin), Worn Again, Evrnu, Re:newcell, Ioncell, Ambercycle, and others are still active. Since textiles can be made of many various types of materials, recycling them can be challenging; nonetheless, the focus of this research is only on recycling cotton and polyester.

2 Pre-process of Recycling Recycling of textiles can only be achieved when there are proper collection and sorting mechanisms are available. It is a very strenuous job to collect used textiles from different areas. Separating the collected waste is more challenging because it is very difficult to identify the composition of the waste. Though there are different technologies available that help in the separation of the collected waste depending on the composition, color, and many other factors.

2.1 Collection of Textiles According to the Indian Textile Journal, more than 1 million tons of textiles are thought to be thrown away annually, the majority of which comes from domestic sources. 13 million tons of textiles were thrown away in the United States in 2017, and 85% of them were either burned or dumped in landfills, according to the BBC [3]. Every year, the average American discards about 37 kg of clothing. According to estimates, a garbage truck’s worth of clothes is thrown into landfills every single

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Country wise data for textile waste (Kg/capita) 60.2 UK

19 7 7 7 6 6 5 4 0.79

Portugal Austria Norway

India 0

10

20

30

40

50

60

70

Fig. 1 Country wise textile waste

second, and 92 million tons of textile waste are produced annually in the world. According to the graph below, the United Kingdom, Italy, Portugal, EU-28, Austria, Germany, Norway, and Sweden, each dispose of 19, 7,6,6,5,4,1,1 kg of textile waste per person (Fig. 1). The Environmental Protection Agency (EPA) [4] tracks how much textile waste is generated, recycled, composted, burned with energy recovery, and disposed of in municipal solid waste (MSW). According to the EPA, 17 million tonnes of textiles were produced in 2018. The American Apparel and Footwear Association’s sales data was used in part to determine generation estimates for apparel and footwear. The EPA also discovered that a sizeable number of textiles enter the market for reuse, however, this amount is not taken into account when estimating textile generation. Wiper rags and old clothing eventually find their way into the trash stream and contribute to the production of MSW (Fig. 2). Charitable organizations. The most popular method for collecting used textiles separately is to give them to non-profit organizations. Usually, the collection is done using textile bins that are located in recycling facilities, public areas, or corporate centres, as well as second-hand stores. Either the municipality or the non-profit organization can empty the containers and transport the textiles gathered. The proceeds from the trade and collection of worn textiles are utilized by charitable organizations (e.g. Salvation Army, etc., in UK) [5] to support their operations and carry out their aims. • The used textiles may also be given (or sold) to various private businesses. The actors employ a variety of techniques to gather used textiles, such as kerbside collection, textile container collection, and in-store collection. These actors include, for instance: • Commercial collectors (such as private garbage management organizations and recycling businesses).

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Fig. 2 Textile waste data. Source Environment protection agency, 2018

• Second-hand shops (not operated by governments or non-profit organizations). • Clothing retailers like H&M and Jack & Jones work with I: Collect to collect textiles for recycling or reuse. • Stores that sell clothing gather unwanted textiles for resale and campaigns (such as WRAP). • Clothing banks such as Salvation Army • These performers might just be employed for commercial purposes or they might work with charities (i.e. passing on the collected textiles). Municipality. Municipal waste management organizations can collect used clothing at the roadside, in textile bins, or in recycling facilities. Municipalities can also hire (private) waste hauliers to collect textile waste and old clothing as a different collection method. Municipalities can work with non-profit groups, for instance, allowing them to set up collection bins in recycling facilities and other public areas. In these situations, the municipalities may be in charge of emptying the containers (like with Fretex in Norway) or the charitable organizations may handle this task independently (e.g. UFF in Norway). The textiles that have been discarded in the residual waste are collected by municipal waste providers.

2.2 Separation of Polyester and Cotton End textile waste needs to go through various pretreatment stages before the chemical process of recycling. The pretreatment method for 100% cellulose and polyester is easy whereas the main challenge comes for polycotton. It is very difficult to separate

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polyester and cellulosic at fibre from polyester cotton blend. The first strategy is to dissolve the cotton while keeping the PET in place. Jeihanipour et al. [6] employed this strategy, dissolving the cotton component in NMMO to separate it from the polyester. Following regeneration, the cotton was digested to produce biogas. Cotton may be separated from poly cotton blend using ionic liquids, as demonstrated by De Silva et al. [7], BBC [8]. These authors suggested that the recovered PET might be melted down to create fibres or bottles and that the cotton could be utilized to make fibres or films. This method has been patented by Evrnu ® [9]. The patented technology uses ionic liquids to dissolve cellulose and the solid portion of polyester is extracted (Fig. 3).

Fig. 3 Schematic overview of poly-cotton. Source Björquist Stina 2017

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3 Recycling Technology Throughout their lifespan, textiles have a major negative impact on the environment. One of the most polluting and waste-producing businesses in the world is the global textile industry, which uses a lot of water, energy, pesticides, and fertilizers. Textile recycling is a way to extract textile waste from landfills. There are two ways of recycling mechanical and chemical. Mechanical recycling is not fibre specific, any type of textiles can be shredded and mechanically recycled. Whereas in chemical recycling different types of chemicals are used depending on the composition of the textiles for recycling. The recycling of cotton polyester blend can be categorized in three different ways. First, the way Infinted Fibres of Finland uses their technology, in which only cotton is being recycled and polyester comes as byproduct of the process which is then being used for other purposes like energy generation, etc. Then comes some chemical recycling technology which only recycles polyester out of cotton polyester blend. The third method which is the complete recycling technology which is patented by Evrnu in which both cotton and polyester are recycled. Cellulose is being recycled first and polyester is precipitated and then is being recycled using other chemicals.

3.1 Different Types of Chemical Recycling Methods for PET Polyester is the most recyclable polymer in the world. PET is a type of polyester that contains functional ester groups that may be broken down by a number of reagents, including water (hydrolysis), alcohols (alcoholysis), acids (acidolysis), glycols (glycolysis), amines (aminolysis). Most commonly, recycled PET is used to create fibres, films, foams, sheets, bottles, and other products. The following categories comprise the chemical recycling processes for PET: hydrolysis, glycolysis, methanolysis, and other reactions (Figs. 4 and 5). The chemical recycling of PET is discussed in detail in this paper, Hydrolysis. By adding water in an acidic, alkaline, or neutral environment, PET is depolymerized into terephthalic acid (TPA) and ethylene glycol. The hydrolysis byproducts can be transformed into more expensive compounds like oxalic acid or utilized to create virgin PET. For acid hydrolysis, concentrated sulfuric acid is typically utilized, caustic soda is used for alkaline hydrolysis, and water or steam is used for neutral hydrolysis. Because water is the weakest nucleophile of the three depolymerizing agents (methanol, ethylene glycol, and water), hydrolysis occurs slower than methanolysis and glycolysis (Fig. 6). Methanolysis. PET is broken down by methanol into dimethyl terephthalate (DMT) and Ethylene glycol (EG) as shown in Fig. 7 which is known as methanolysis. The high cost of separating and purifying the mixture of reaction products is one disadvantage of this technology.

Decoding the Science Behind the Chemical Recycling of Textiles

TPA

301

Polyols

BHET

Hydrolysis

Glycolysis

PET

Repolymerization

Methanolysis

DMT

Aminolysis

Ammonolysis

BHETA

TPA Amide

Fig. 4 Depolymerization of PET

Chemical Recycling of PET

Other Processes

Glycolysis

Hydrolysis

Methanolysis

Main Product

Main Product

Main Product

Aminolysis

BHET + Oligomer

+ ETPA G

DMT + EG

Ammonolysis

Acid

Alkaline

Neutral

Fig. 5 Chemical recycling of PET

Additionally, water can poison the catalyst and create other azeotropes if the process is disturbed. Glycolysis. Ethylene glycol is utilized in glycolysis to create PET glycolyzates such as bis(2-hydroxyethyl) terephthalate shown in Fig. 8 which can be used to create unsaturated resins, co-polyesters, acrylic coatings, and hydrophobic dyestuffs. Fresh BHET can be combined with BHET produced through glycolysis, and the resulting combination can be used in either of the two PET synthesis lines (based on DMT or TPA). As a solvent for the PET glycolysis process, diethylene glycol, tri-ethylene glycol, propylene glycol, or di-propylene glycol may also be utilized. In addition to being

302 Fig. 6 Hydrolysis of PET

Fig. 7 Methanolysis of PET

Fig. 8 Glycolysis of PET

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flexible, glycolysis is the oldest, least complex, and capital-intensive process. Due to these factors, the glycolysis of PET has received a lot of interest. The reaction has been carried out under a variety of temperature and time conditions. There are four different methods for the glycolysis of postconsumer PET materials: (i) Solvent-assisted glycolysis- It involves the ethylene glycol-mediated breakdown of PET in the presence of a solvent. In the zinc acetate catalyzed PET glycolysis procedure, xylene is added, and a greater BHET yield than with xylene is achieved. Initially, xylene’s primary goal was to make the PET-glycol mixture more mixable. EG dissolves weakly in xylene at temperatures between 170 and 225 °C, but quickly in PET. The glycolysis by-products, meanwhile, are soluble in xylene. As a result, the glycolysis products shifted from the PET-glycol phase to the xylene phase as the reaction developed, altering the reaction’s direction toward depolymerization. (ii) Supercritical glycolysis- At temperatures and pressures over ethylene glycol’s critical point, a process known as supercritical glycolysis uses ethylene glycol to break down PET. Supercritical conditions have just recently been investigated for glycolysis, compared to prior research on PET hydrolysis and methanolysis [10]. The fundamental benefit of using supercritical fluids in a process is that catalysts, which are challenging to remove from the reaction products, are no longer required. Additionally, it protects the environment. (iii) Microwave-assisted glycolysis- Pingale and Shukla [11] expanded their research beyond eco-friendly catalysts to include the utilization of unconventional heating sources like microwave radiations. The use of microwave radiation as a heating source significantly cut the reaction’s completion time from 8 h to just 35 min. However, the yield of BHET monomers was not increased. The BHET yield may be increased while the reaction time is reduced by using a more effective catalyst in combination with microwave irradiation heating. (iv) Catalyzed glycolysis- Without a catalyst, glycolysis proceeds very slowly. For the depolymerization of PET to BHET, there has been considerable interest in the development of extremely active transesterification catalysts. Catalysis is the most researched strategy for speeding up glycolysis. An example of a transesterification reaction is PET glycolysis. In order to speed up PET glycolysis, trans-esterification catalysts have been used, with metal-based catalysts being the most common. Aminolysis. When recycled PET is subjected to a variety of primary amine solutions, including methylamine, ethylamine, ethanolamine (EA), allylamine, and hydrazine in an aqueous form, diamides of TPA and EG are formed [7]. This is known as bis(2-hydroxyethylene) terephthalamide (BHET) as shown in Fig. 9. Till now there are no such reports available that state the commercial use of this process of PET recycling. But it is evident that partial aminolysis is helpful in increasing the property of fibres during manufacturing with defined processing properties.

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Fig. 9 Aminolysis of PET

Ammonolysis. Action of ammonia on PET in the presence of ethylene glycol produces Terepthalamide as shown in Fig. 10 it is also possible to do PET ammonolysis under low pressure using ammonia as the degradation agent in an ethylene glycol environment. The reaction is catalyzed by zinc acetate in a concentration of 0.05 weight per cent, carried out at 70 degrees Celsius, and results in the production of 1:6 PET-NH3 terephthalamide with an approximate yield of 87%. Fig. 10 Ammonolysis of PET

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3.2 Different Types of Chemical Recycling Methods for Cellulose Ionic Liquids. Technology for processing cellulose using ionic liquids (ILs) has great promise for commercialization. Many ILs are attractive for the manufacturing of cellulose-based fibres and materials due to their chemical and thermal stability, as well as their solubility with other solvents. The most researched ILs for cellulose dissolving and rejuvenation are those based on imidazolium cations. The process’ sustainability and capacity to dissolve cellulose are both impacted by the cation and anion combinations used. As spin dopes for forming cellulose into fibres, popular imidazolium-based ILs such BuMeImCl, 1-ethyl-3-methylimidazolium chloride, and 1-ethyl-3-methylimidazolium acetate were compared with NMMO. Since NMMO dissolves cellulose and facilitates the synthesis of fibres during the regeneration process, it is a frequently used solvent for the manufacturing of cellulose fibres. But NMMO has a number of drawbacks, including as high toxicity and the need for a lot of water for solvent recovery. Since they have various benefits over NMMO, including as low toxicity, excellent thermal stability, and the capacity to dissolve cellulose at lower temperatures, imidazolium-based ILs have come to be thought of as a viable replacement. In the effective synthesis of cellulose fibres with good mechanical qualities, these ILs have been employed. BuMeImCl, one of the researched imidazolium-based ILs, has demonstrated potential as a spin dope for the synthesis of cellulose fibre. It is very compatible with other solvents, has a low viscosity, and a strong ability to dissolve cellulose. Additionally, the high tensile strength and exceptional thermal stability of fibres made from BuMeImCl-based spin dopes have been demonstrated. In general, imidazolium-based ILs have the potential to replace NMMO in the synthesis of cellulose fibres, with BuMeImCl standing out as a viable alternative. However, more investigation is required to improve the procedure and compare the effects of ILs on the environment to those of conventional solvents [12]. Regeneration of Cellulose from Alkaline Solutions without and with Additives. Budtova and Navard provided a thorough critical analysis encompassing every element of the dissolution of cellulose in aqueous NaOH solvents, including mechanisms of swelling and dissolution, the influence of additions, as well as the properties of materials created from these solutions. This solvent system’s low cost, potential for wide-scale application, and relatively easy chemical recycling are all clear benefits. In general, the qualities of the regenerated cellulose fibres are comparable to those of viscose, however they are less than those of Lyocell. Regeneration of cellulose into fibres from solvents based on aqueous NaOH was reported by numerous groups. The need for a low cellulose dissolution temperature, the limited stability of the biopolymer solutions, the low cellulose DP and concentrations that can be used, as well as a need for additives, are some of the reasons why NaOH-based cellulose solvents have not yet reached full-scale industrialization. Some of these problems, though, might not be as severe as to prevent large-scale production, as new patents

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detail a cellulose dissolution and spinning process in a NaOH-based system, along with a method for chemical recovery [13]. Cellulose Carbonate and Carbamate Processes. Similar to the viscose method, it is also feasible to use different cellulose derivatives, dissolve them in diluted alkali, and then precipitate the resulting fibres in an acidic coagulation bath. In particular, eliminating the usage of CS2 and the release of H2 S (harmful, volatile, and flammable) during the production of viscose has significant environmental benefits [14]. Cellulose carbonate is a possible alkali-soluble cellulose derivative that can be produced in both heterogeneous and homogeneous reaction environments. The method used by Oh et al. to create cellulose carbonate by reacting soda-cellulose with CO2 at pressures between 40 and 50 bar while including ZnCl2 and acetone or ethyl acetate seems intriguing. The derivative was then dissolved in NaOH with zinc oxide (ZnO) and the mixture was wet spun into continuous filaments using coagulation baths of acid/water or acid/salt/water. The finished fibres had mechanical characteristics resembling those of viscose rayon fibres.

4 Regenerated Form of Cellulose and Polyester 4.1 Micro and Nanoparticles The cellulose or cellulose derivative solution should be dropped into a coagulation medium in order to produce spherical-shaped cellulose particles in the quickest and easiest manner possible. As an alternative, pure cellulose particles can be made from cellulose derivatives, such as viscose or cellulose carbamate, by hydrolysis during the coagulation process, or in a separate phase following particle production and separation (cellulose acetate, CA). The type and size of the syringe or nozzle employed determines the particle size; the minimum attainable diameter is fairly high, ranging from 250 to 500 m [15]. Dispersive treatments can be used to produce smaller particles.

4.2 Films and Membranes Cellophane, the first regenerated cellulose membrane or film, was created straight from the viscose process. The viscose mixture is injected through a slit into a bath of diluted sulfuric acid in order to create a transparent cellophane film rather than a fibre. After fibres, cellulosic films are the type of material that is used most frequently. There are many commercially available cellulose and cellulose derivative films that are used as packaging material and in separation processes like filtration. The preparation technique that is most frequently used is the coagulation of cellulose or a cellulose derivative solution in a suitable non-solvent. The film qualities are governed by the

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cellulose type, concentration, and coagulation conditions. To change the film characteristics, additives such metal and metal oxides, activated carbon, and polymeric nanoparticles were used.

4.3 Nonwoven Materials Cellulosic nonwovens are sheet- or web-like structures made of entangled filaments or fibres of cellulose with small diameters, often in the nano to micrometer range. Both hydrophilic and hydrophobic interactions are used to interact between them. These interactions can be improved through chemical modification or treatment, for as with cross-linking agents, allowing nonwovens to have customized properties like absorbency or liquid repellence. Nonwovens are therefore typically utilized in textiles, hygiene products, filters and membranes, medical applications (wound treatment), and packaging materials. Nonwovens can be produced without spinning cellulose fibres into yarns, in contrast to the manufacturing of cellulose fibres.

4.4 Cellulose Regeneration as Fibres The viscose technique (derivatizing) and the Lyocell process are the two commercial methods for creating regenerated cellulose fibres (non-derivatizing). In order to create high-performance fibres, the viscose process relies on the synthesis of cellulose xanthogenate, which is then dissolved in NaOH and wet spun. In contrast, the Lyocell method relies on the physical breakdown of cellulose in N-Methylmorpholine N-oxide (NMMO) and the creation of fibres through dry-jet wet spinning into an aqueous precipitation bath [16]. You may find more details about these business procedures, including their advantages and disadvantages, elsewhere. The current account on cellulose fibre regeneration will concentrate on solvent systems that could be crucial for industrial processes, including certain ILs that include salts of super-bases.

4.5 Polyester Regeneration as Chips The polyester is regenerated in the form of small chips after recycling. A plastic bottle is mechanically recycled by being washed, shredded, and then converted into polyester chips, which are then put through the conventional process of creating fibre. Chemical recycling is the process of repurposing old plastic into its original monomers, which are identical to new polyester. Then, those might rejoin the conventional polyester production chain.

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5 Analysis of Companies for Chemical Recycling This research covers a study of 100 companies which are directly or indirectly associated with textile recycling. The purpose of studying the companies was to understand about the actual technology holder of chemical recycling which we have coined as ‘Converters’. The converters are the main players who are holding the technologies for textile recycling using chemicals. The study has total of 28 converters out of which 14 are patent holders. Remaining companies are using the technology of their own or may be some other’s technology. Those companies have not mentioned clearly about those facts. The analysis of the patented technologies has been done further in this paper. It was discovered during the analysis of the supply network that the organizations can be grouped into three concentric circles. Government and non-government organizations, think tanks, trade associations, certification agencies, foundations, etc., are the main external players. They are primarily involved in raising public awareness among the general public and in industry circles, as well as in the development of standards, certification, and policy. Developers of technology, many of whom are also producers, make up the innermost core. Contract manufacturers and marketers make up the middle layer; they brand and rebrand items and services, building the crucial link between the outermost layer and the innermost core. In this study, 100 such organizations were examined, and only 25% of them were discovered to be true manufacturers.

6 Patent Analysis 6.1 Continent Wise Patent Count1 S. no

Company

Patent no

Country

Assignee/applicant

Year of filling

1

Aqufil2

US 005169870A

Italy

BASF corporation,

21 June 1991

2

Evrnu

WO 2017/ 019802 A1

US

EVRNU SPC

27 July 2016

3

Evrnu

US 2016/ 0369456 A1

US

EVRNU SPC

28 July 2015 (continued)

1 Twelve patent documents were accessible out of sixteen patented technologies. Out of twelve analyzed patents two companies are having two patented technologies under them. So, total 14 patented technologies holders have been studied in this research. 2 Only one patent which is Aquafil’s patent has been expired.

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(continued) S. no

Company

Country

Assignee/applicant

Year of filling

4

Infinited fibre US 2015/ 0225901 A1

Patent no

Europe

Technologian Tutkimuskeskus VTT Oy

16 September 2013

5

Infinited fibre WO 2018/ 197756 A1

Europe

Infinited fiber company OY

27 April 2018

6

Ioncell

WO 2018/ 138416 A1

Europe

AALTO University Foundation SR, Helsingin Yliopisto

30 January 2018

7

Jelpan

US 7,193,104 B2

Japan

Aies Co. td

18 June 2003

8

Lenzing

US 2020/ 0347520 A1

Europe

Lenzing Aktiengesellschaft

14 January 2019

9

Milliken

WO 2018/ 150028 A1

US

SWEREA IVF AB

20 February 2017

10

Re:Newcell

EP 2817448B1

Europe

Re:Newcell Lux

19 February 2013

11

Tyton BioSciences

US 10501599B2

US

Tyton biosciences, LLC, Danville

11 January 2019

12

WornAgain

WO 2014/ 045062 A1

London, UK

Worn again footwear and accessories ltd

23 September 2012

13

Unifi

–

US

–

–

14

Gr3n

–

Europe

–

–

15

Ambercycle

–

US

–

–

16

Loop Industries

–

Canada

–

–

After analyzing the existing patented technologies for textile chemical recycling, it was found that patents were filed between the periods of 2003–2019. This means that the first patent will be commercially available after 2023, whereas most of the patents will be commercially available after 2030–2035, which is approximately 10 years of the time period from now. From Fig. 11 it is evident that Europe is the biggest player in holding patented technologies in chemical recycling of textiles. Many countries of North America are also patent holders whereas Asia is lagging behind in this competition. Only one country Japan is having the patented technology in textile recycling (Fig. 12). While analyzing the patents it was realized that somewhere patents are using almost similar kind of chemicals, the major difference accounted for was in the conditions like temperature, pressure, volume of the chemicals, etc. (Figs. 13 and 14).

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Think Tank

Facilitator

Converter

Fig. 11 Zones of recycling tech

Fig. 12 Continent wise patents

Decoding the Science Behind the Chemical Recycling of Textiles

311

Fig. 13 Countries with patented technology for chemical recycling

Chemical recycling process

Hydrolysis 46%

Carbamation 18%

Glycolysis 9%

Carbamation Glycolysis

Depolymerisation 27%

Depolymerisation Hydrolysis

Fig. 14 Patent analysis based on chemical technologies

6.2 Chemical Technology Based Patents

Italy

Aqufil

Evrnu

Evrnu

Infinited fibre

Infinited fibre

Ioncell

Jelpan

Lenzing

Milliken

Re:Newcell

Tyton BioSciences

WornAgain

1

2

3

4

5

6

7

8

9

10

11

12

London, UK

US

Europe

US

Europe

Japan

Europe

Europe

Europe

US

US

Country

S. no Company

WO 2014/045062 A1

US 10501599B2

EP 2817448B1

WO 2018/150028 A1

US 2020/0347520 A1

US 7,193,104 B2

WO 2018/138416 A1

WO 2018/197756 A1

US 2015/0225901 A1

US 2016/0369456 A1

WO 2017/019802 A1

US 005169870A

Patent no

Polyester (Fabric, plastics frm pckaging (Food), plastic bottles)

Cellulose & polyester

Cellulose

Polyester

Cellulose

Polyester

Cellulose

Cellulosic fiber (Post consumer, pre consumer)

Cellulosic fiber (Cardboard)

Cellulosic fiber (Textile waste)

Cellulose & polyester

Nylon 6 (e- caprolactum) (Carpet)

Material

Carbamation

Glycolysis

Depolymerization

Hydrolysis

312 S. Singh and P. Jana

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There are many different chemicals that are being used in all the technologies of chemical recycling. Most of the technology holders are using hydrolysis method for recycling which is almost 46% and depolymerization is 27%. Hydrolysis is being used to recycle both cellulose as well as polyester materials whereas depolymerization is mainly used for polyester recycling. Other method such as carbamation is only used for dissolving cellulose. Till now only one company is having patent for this technology which is Infinited Fibre. Japan is the only company in the list which has the patent for the glycolysis technology, which is for dissolving polyester. The above mentioned patents are related to the recycling method of cellulose and polyester, only one patent is about recycling Nylon 6. The patent holder of this technology is Aquafil. Out of the remaining patents 6 are cellulose recycling technology, 3 are polyester recycling technology and 2 are about the recycling method of polyester cotton blend. It indicates that most patented technologies deal with cellulose recycling method using different chemicals.

6.3 Patent Classifications

Sl. no

Patent class

Definition

1

C08

Organic macromolecular compounds; their preparation or chemical working-up; compositions based thereon

C08B

Polysaccharides per se or their derivatives, with six or more repeating units, i.e. saccharide radicals attached to each other by glycosidic linkages. Processes of extraction, preparation, derivatization, fractionation, isolation, purification or degradation. Covalently or ionically cross-linked gels of polysaccharides

C08J

Chemical aspects of processes for treating, compounding, working-up or recovery of macromolecular substances unless the treatment, compounding, working-up or recovery is provided for elsewhere as indicated below in the relationship section. Chemical features of manufacture, treatment or coating of articles or shaped materials containing macromolecular substances unless the manufacture, treatment or coating is provided for elsewhere as indicated below in the relationship section. Chemical aspects of working-up of macromolecular substances to porous or cellular articles or materials and after-treatment thereof unless provided for elsewhere as indicated below in the relationship section. Chemical aspects of recovery or working-up of waste materials, i.e. macromolecular materials (e.g. polymers), solvents and unreacted monomers, unless provided for elsewhere as indicated below in the relationship section

C08L

The technical field for compositions of polymers

C07

Organic Chemistry

C07C

Acyclic or carbocyclic (alicyclic) low molecular weight organic compounds Processes for the preparation of acyclic or carbocyclic (alicyclic) low molecular weight organic compounds, whereby preparation also includes purification, separation, stabilization or use of additives

2

(continued)

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(continued) Sl. no

Patent class

Definition

3

D01

Natural or Man-made Threads or Fibres; Spinning

D01F

Chemistry-related aspects in the manufacture of artificial fibres, filaments and similar. It also covers–the chemical treatment of fibres and filaments during their production, e.g. before winding,

D06

Treatment of Textiles or The Like; Laundering; Flexible Materials Not Otherwise Provided For

D06M

The chemical and physical treatment of fibrous materials in any form like fibres, nanofibres, microfibres, threads, yarns, knits, fabrics, nonwovens, feathers made from organic natural, synthetic macromolecular compounds or carbon to modify their properties or impart specific functions

D21

Production of Cellulose

D21C

Production of cellulose by removing non-cellulose substances from cellulose containing material. This subclass also embraces the after treatment of cellulose pulp and the regeneration of pulp liquors. It further also covers different aspects of digesters for pulping cellulosic material

D21H

Pulp compositions for paper manufacturing, papers obtained therefrom, coated papers and impregnated paper. It also covers the processes for adding materials to pulp or papers and after-treatments of papers as well as special papers

4

5

See Fig. 15. Fig. 15 Shows that most of the patents fall in the category of C08 patent class which deals with organic macromolecular compounds; their preparation or chemical working-up and their compositions. Out of 12 patents analyzed 9 falls under this category

Patent Classification 16% 5% 47% 16% 16%

Decoding the Science Behind the Chemical Recycling of Textiles

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7 Conclusion In essence, it can be said that chemical recycling is a cutting-edge field with tremendous potential. Another thing that may be expected is that modern businesses will dominate the textile recycling industry, taking the place of traditional, 100-year-old textile technology suppliers. To further our understanding of the past, present, and future uses of the important recycling technologies, this study also highlights the details of different existing patent technology of different countries. This information will be beneficial for further studies about the chemical recycling technology. In summary, it can be concluded that chemical recycling is in the development stage and offers incredible future prospects. It can also be predicted that textile recycling technology will be ruled by new-age companies, a shift from traditional century-old textile technology suppliers. Additionally, the analysis presents many viewpoints for potential future developments in recycling technology applications, which is helpful for both academic and non-academic scholars interested in the subject as well as practitioners.

Annexure 1 Distinguishing Converters, Facilitators and Think Tanks To clearly understand the difference among converters, facilitators and think tanks I constructed a set of questions based on the organizations studied. These questions cover all the key functions of the organizations listed in this paper. The questions are listed below: 1. How do you describe your organization the best? My organization … 2. Donate funds for conducting research on textile recycling/Start-ups which are into sustainability or circularity 3. Is not a converter for recycling textiles but raise funds (receive funds) for conducting research on textile recycling 4. Is not a converter for recycling textiles, but creates awareness about textile circularity among different stakeholders 5. Aggregates information about suppliers of recycled textiles and provides to brands/manufacturers who are likely to use the recycled textiles 6. Aggregates information about demand of recycled textiles and provides to textile recyclers (converters) 7. Is a platform which collects different sorts of textile waste and gives it to converters for recycling 8. Is a platform which collects post-consumer textiles and donates it to charitable trusts.

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9. Is a platform that aggregates information in demand as well as supply side of recycled textiles and does the matchmaking 10. Develop different specifications of recycled textiles in partnership with textile recyclers (converters) and we own the brands of recycled textiles 11. Is advising consumers/brands/retailers how to best adopt the textile circularity concept. 12. Is advising apparel manufacturers/textile manufacturers how to best adopt the textile circularity concept. 13. Is devising policy regarding textile circularity in consultation with multiple stakeholders like brands/retailers/ apparel manufacturers/textile manufacturers/ Government/NGO 14. Is a Govt. body for offering certification mark for the authenticity of recycled textile material 15. Is a non-Govt. body for offering certification mark for the authenticity of recycled textile material 16. Is non-profit part of a retail brand which encourages research in textile recycling/ sustainability 17. Is a forum to develop concrete public–private partnerships at scale to deliver on textile recycling?

Annexure II List of Companies Analyzed

Sl. no

Company name

Incorporation year

Country of origin

1

Accelerating circularity

2020

Europe

2

Carbios

2011

France

3

P4G (Circular fashion partnership)

2021

Sweden

4

Cyclo

−

Bangladesh

5

Circular systems

2017

Los Angeles

6

Cradle to cradle

2005

German

7

Ellen MacArthur foundation

2009

Isle of Wight, UK

8

Euric textiles

2018

Europe

9

Evrnu

2014

Seattle, US

10

Fashion for good

2017

Amsterdam

11

Gren

2011

Switzerland

12

Infinited fibre

1990

Finland (continued)

Decoding the Science Behind the Chemical Recycling of Textiles

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(continued) Sl. no

Company name

Incorporation year

Country of origin

13

Loop industries

1938

Austria

14

Milliken

1865

Spartanburg, South Callifornia

15

Oerlikon

1906

Switzerland

16

Petcore Europe

1993

Brussels

17

Fashion positive

2014

San Francisco

18

Re:newcell

2012

Sweden

19

Sulzer

1834

Switzerland

20

Textile exchange

2002

USA

21

Unifi

2006

America

22

Wornagain

2005

London

23

Ecoplanet

2010

UK

24

Demeto

2003

Switzerland

25

Wrap

2000

UK

26

Nordic bioproducts group

2019

Finland

27

Tyton biosciences

2011

Danville, Verginia

28

Ioncell

2009

Finland

29

Jeplan

2007

Japan

30

Environmental European Beauro

1974

Europe

31

Ambercycle

2013

Los Angeles, US

32

Aquafil

1965

Italy

33

Phoenxt

−

Berlin

34

Cycora

2019

US

35

Rev

−

Netherland

36

FENC

−

Taiwan

37

BlockTexx

2018

Australia

38

Pro India recycling

2018

India

39

Enviu

2004

Netherland

40

Upparel

2016

New Zealand

41

Teijin

1918

USA

42

Sustainable apparel coalition

2009

Amsterdam

43

EASTMAN

1920

U.S

44

SaXcell

2015

Netherland

45

Protein evaluation

2021

US

46

I:Co

−

Germany

47

Loop industries

2015

Canada

48

Texaid

1978

Switzerland (continued)

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(continued) Sl. no

Company name

Incorporation year

Country of origin

49

Frankenhuis

−

Netherland

50

Boer group

2015

Netherland

51

Sympany

2015

Netherland

52

Sussan (Retail Brand)

1939

Australia

53

Pure waste

2013

India

54

Mud jeans

2012

Netherland

55

Patagonia

2005

North America (US)

56

Levi’s strauss

1853

North America (US)

57

Vetta

−

North America (US)

58

Universal standard

2015

North America (New York)

59

Girlfriend collective

2016

Seattle, Washington

60

Reformation

2009

North America (US)

61

ReGain

−

Europe (UK)

62

BB engineering (Mechanical)

1997

Europe (Germany)

63

Sortile

2021

North America (NY)

64

Recycled blended claim standard

2017

65

Global recycled standard

2017

66

SGS

1878

Europe (Geneva Switzerland)

67

OEKO-TEX 100

1992

Europe (Germany)

68

Salvation army

1865

Europe (UK)

69

FabScrap

2016

North America (NY)

70

Vivify textiles

2016

Australia

71

Kishco group

1938

India

72

Textile recycling association

1995

Europe (Uk)

73

Circ

2011

Virginia

74

Hong Kong research institute of textiles and apparel

2006

Sweden (H&M Retail)

75

Balkan

1951

Turkey

76

Dell Orca Villani

1964

Italy

77

Andritz Laroche

1954

France

78

Lidem

1994

Spain

79

Margasa

1987

Spain

80

Masias

1993

Spain

81

OMMI (Patented)

1963

Italy

82

Pure loop

2015

Austria (continued)

Decoding the Science Behind the Chemical Recycling of Textiles

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(continued) Sl. no

Company name

Incorporation year

Country of origin

83

SICAM

1975

Italy

84

Starlinger

1987

Australia

85

HSN machienry

2007

India

86

Billie upcycling

2019

Hong Kong

87

PurFi

1925

US

88

Rewoven

2018

South Africa (Cape Town)

89

CETI

2020

90

ANDRITZ

1852

Austria

91

Interreg fibersort

−

Netherland

92

Valvan bailing system

1997

Belgium

93

Recover

−

Spain

94

Eurofios

2015

Brazil

95

JF fibras

2004

Brazil

96

Shreeji cotfab

1995

India

97

Usha Yarns Limited

1995

India

98

Procotex

1970

Belgian

99

Anandhi texstyles

−

India

100

Miller waste mills

1927

Poland

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9. About Us: United States Environmetal Protection Agency (2022) United States Environmetal Protection Agency. https://www.epa.gov/facts-and-figures-about-materials-waste-andrecycling/textiles-material-specific-data 10. Büyükaslan E, Jevsnik S, Kalo˘glu F (2015) A sustainable approach to collect post-consumer textile waste in developing countries. Marmara J Pure Appl Sci 1:107–111 11. Jeihanipour A, Karimi K, Niklasson C, Taherzadeh MJ (2010) A novel process for ethanol or biogas production from cellulose in blended-fibers waste textiles. Waste Manage 30(12):2504– 2509 12. Sayyed AJ, Deshmukh NA, Pinjari DV (2019) A critical review of manufacturing processes used in regenerated cellulosic fibres: viscose, cellulose acetate, cuprammonium, LiCl/DMAc, ionic liquids, and NMMO based lyocell. Cellulose 26:2913–2940 13. Staey F, Christopher S (2016) United States Patent No. 14/811,723 14. Imran M, Kim BK, Han M, Cho BG (2010) Sub-and supercritical glycolysis of polyethylene terephthalate (PET) into the monomer bis (2-hydroxyethyl) terephthalate (BHET). Polym Degrad Stab 95(9):1686–1693 15. Pingale ND, Shukla SR (2008) Microwave-assisted eco-friendly recycling of poly (ethylene terephthalate) bottle waste. Eur Polymer J 44(12):4151–4156 16. Thomas S, Rane AV, Kanny K, Abitha VK, Thomas MG, (Eds.) (2018) Recycling of polyethylene terephthalate bottles. William Andrew